Sec 2 G1 Maths Tutor Bukit Timah

Reader note: Every journey, activity and rate is an original hypothetical teaching example, not a real transport timetable, speed limit, safety claim or examination question. Uniform movement and constant production are assumptions when used. Confirm tuition availability, fees, tutor allocation and learning needs directly.

Bring one incorrect unit-conversion and one average-speed problem to a parent–student enquiry with eduKate Singapore. Ask for a diagnosis of the first wrong operation rather than another worksheet of identical sums.

Official references and reader note

Monday: derive the 3.6 conversion factor from 1000 and 3600, then convert six speeds both ways.
Tuesday: convert minutes and mixed hours into decimal hours and back.
Wednesday: solve two questions each for distance, speed and duration.
Thursday: find total distance and elapsed time for two-stage journeys; include one with a stop.
Friday: practise non-travel rates, then re-solve the week’s first mistaken calculation without viewing the answer.

A parent can ask, ‘What does your answer measure, and which units remain when you divide?’ If the student can explain both and correctly reverse-check a changed journey, the method is becoming independent rather than merely familiar.

G1 subject level and the published 2027 SEC syllabus

MOE’s Secondary Two G1 content names rates and average rates, speed and average speed, and conversions such as km/h to m/s. The 2027 SEC K110 G1 Mathematics syllabus retains these numeric rate skills. Its graduating-exam requirements belong to 2027 candidates, not necessarily a pupil currently in Secondary 2 in 2026. This guide deliberately avoids claiming that distance-time or speed-time graph interpretation is a required K110 topic. Use the school’s actual assessment sequence and later the official syllabus for the learner’s own cohort.

Frequently asked questions

faq1

Because one kilometre is 1000 metres and one hour is 3600 seconds; 1000/3600=1/3.6.

faq2

Yes. It is calculated from total distance divided by total elapsed time. The result generally lies between relevant positive stage speeds when combining ordinary moving stages, but need not equal either stage speed.

faq3

It counts when the question defines total elapsed journey time to include that stop. Read the requested interval carefully.

faq4

The stages may have unequal durations or distances. The whole-trip average comes from total distance and total time; an unweighted mean can be wrong.

faq5

The underlying concept is the same: output divided by time. Preserve the actual units such as pages/min or L/min.

faq6

Yes. It is explicitly listed in the MOE Secondary Two G1 N4 content. School assessment dates and emphasis vary.

Official references and reader note

Monday: derive the 3.6 conversion factor from 1000 and 3600, then convert six speeds both ways.
Tuesday: convert minutes and mixed hours into decimal hours and back.
Wednesday: solve two questions each for distance, speed and duration.
Thursday: find total distance and elapsed time for two-stage journeys; include one with a stop.
Friday: practise non-travel rates, then re-solve the week’s first mistaken calculation without viewing the answer.

G1 subject level and the published 2027 SEC syllabus

Frequently asked questions

faq1

Because one kilometre is 1000 metres and one hour is 3600 seconds; 1000/3600=1/3.6.

faq2

faq3

It counts when the question defines total elapsed journey time to include that stop. Read the requested interval carefully.

faq4

The stages may have unequal durations or distances. The whole-trip average comes from total distance and total time; an unweighted mean can be wrong.

faq5

The underlying concept is the same: output divided by time. Preserve the actual units such as pages/min or L/min.

faq6

Yes. It is explicitly listed in the MOE Secondary Two G1 N4 content. School assessment dates and emphasis vary.

Official references and reader note

First 10 minutes: retrieve metric and time conversions without a calculator.
Next 20 minutes: derive the speed formulas from units and convert both km/h and m/s.
Next 25 minutes: individual mixed speed and time problems with first-line feedback.
Next 15 minutes: compare stage-speed arithmetic with whole-trip average speed.
Next 10 minutes: unseen mixed rates including print output or liquid flow.
Final 10 minutes: recheck units and plan short retrieval practice.

Five short home sessions

Monday: derive the 3.6 conversion factor from 1000 and 3600, then convert six speeds both ways.
Tuesday: convert minutes and mixed hours into decimal hours and back.
Wednesday: solve two questions each for distance, speed and duration.
Thursday: find total distance and elapsed time for two-stage journeys; include one with a stop.
Friday: practise non-travel rates, then re-solve the week’s first mistaken calculation without viewing the answer.

G1 subject level and the published 2027 SEC syllabus

Frequently asked questions

faq1

Because one kilometre is 1000 metres and one hour is 3600 seconds; 1000/3600=1/3.6.

faq2

faq3

It counts when the question defines total elapsed journey time to include that stop. Read the requested interval carefully.

faq4

The stages may have unequal durations or distances. The whole-trip average comes from total distance and total time; an unweighted mean can be wrong.

faq5

The underlying concept is the same: output divided by time. Preserve the actual units such as pages/min or L/min.

faq6

Yes. It is explicitly listed in the MOE Secondary Two G1 N4 content. School assessment dates and emphasis vary.

Official references and reader note

First 10 minutes: retrieve metric and time conversions without a calculator.
Next 20 minutes: derive the speed formulas from units and convert both km/h and m/s.
Next 25 minutes: individual mixed speed and time problems with first-line feedback.
Next 15 minutes: compare stage-speed arithmetic with whole-trip average speed.
Next 10 minutes: unseen mixed rates including print output or liquid flow.
Final 10 minutes: recheck units and plan short retrieval practice.

Five short home sessions

Monday: derive the 3.6 conversion factor from 1000 and 3600, then convert six speeds both ways.
Tuesday: convert minutes and mixed hours into decimal hours and back.
Wednesday: solve two questions each for distance, speed and duration.
Thursday: find total distance and elapsed time for two-stage journeys; include one with a stop.
Friday: practise non-travel rates, then re-solve the week’s first mistaken calculation without viewing the answer.

G1 subject level and the published 2027 SEC syllabus

Frequently asked questions

faq1

Because one kilometre is 1000 metres and one hour is 3600 seconds; 1000/3600=1/3.6.

faq2

faq3

It counts when the question defines total elapsed journey time to include that stop. Read the requested interval carefully.

faq4

The stages may have unequal durations or distances. The whole-trip average comes from total distance and total time; an unweighted mean can be wrong.

faq5

The underlying concept is the same: output divided by time. Preserve the actual units such as pages/min or L/min.

faq6

Yes. It is explicitly listed in the MOE Secondary Two G1 N4 content. School assessment dates and emphasis vary.

A 60-second diagnostic

Ask a student to convert 72 km/h into metres per second; the answer is 20 m/s. Then ask: ‘A trip covers 60 km in one hour, followed by another 60 km in two hours. What is the overall average speed?’ The answer is 40 km/h, since 120 km/3 h=40. A pupil who obtains 45 by taking the simple average of 60 and 30 has not accounted for the different time intervals. The two errors require different teaching responses.

Speed conversion is a ratio of units

one

One kilometre is 1000 metres. One hour is 3600 seconds. Thus 1 km/h=1000/3600 m/s, or 1/3.6 m/s. Dividing by 3.6 converts the numerical value while preserving the actual physical speed. Check 36 km/h: over one hour it covers 36,000 metres, which is 10 metres each second because 36,000/3600=10.

two

One metre per second describes 3600 metres per hour, which is 3.6 kilometres per hour. Therefore 15 m/s becomes 54 km/h. A student can always derive the relationship from the units when memory fails. The factor is not an arbitrary rule; it is shorthand for two unit conversions.

three

Five metres per second and eighteen kilometres per hour refer to the same movement speed. Neither number is intrinsically more correct; the question’s unit requirement determines which to report. The calculation should attach ‘m/s’ or ‘km/h’ explicitly, since a bare five or eighteen cannot tell a reader what was measured.

Average speed depends on both totals

total

For a two-stage journey, add distances first and add the corresponding times first. If 60 km takes one hour and the next 60 km takes two hours, total distance is 120 km and time is three hours; overall average speed is 40 km/h. Taking an unweighted mean of 60 and 30 gives 45 km/h, which would be incorrect for this unequal-time trip.

rest

If the question asks for the average speed over a journey including a 30-minute stop, the stationary time belongs in elapsed time. A trip of 30 km completed with thirty minutes moving and thirty minutes resting has an elapsed hour and average speed 30 km/h. If the question instead asks for average speed while moving only, the relevant denominator differs. Read the instruction rather than assume all durations mean the same thing.

direction

At a fixed distance, higher speed should mean less travel time. At a fixed speed, more time should produce more distance. A rate calculation that predicts the reverse without new assumptions should be questioned before it is copied into a final answer. This habit catches many incorrect operations when a pupil confuses speed, distance and time.

Original rate, speed and unit-conversion clinics

These 66 original clinics cover both directions of the 3.6 conversion, minutes-to-hours adjustments, multiple stages, stops and other rates such as pages per minute and litres per minute. Work in short groups and let the pupil choose which quantity the question wants before reading the solution.

1. Convert km/h to m/s 1

Question. An imaginary vehicle has a stated speed of 18 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 18×1000/3600 = 18/3.6 = 5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 5 m/s by 3.6 to recover 18 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

Transfer. At 18 km/h for ten seconds, the uniform-motion model predicts 50 m. If the learner can explain the unit cancellation (m/s × s = m), the conversion is meaningful rather than a memorised calculator button.

2. Convert km/h to m/s 2

Question. An imaginary vehicle has a stated speed of 27 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 27×1000/3600 = 27/3.6 = 7.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 7.5 m/s by 3.6 to recover 27 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

Transfer. At 27 km/h for ten seconds, the uniform-motion model predicts 75 m. If the learner can explain the unit cancellation (m/s × s = m), the conversion is meaningful rather than a memorised calculator button.

3. Convert km/h to m/s 3

Question. An imaginary vehicle has a stated speed of 36 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 36×1000/3600 = 36/3.6 = 10 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 10 m/s by 3.6 to recover 36 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

Transfer. At 36 km/h for ten seconds, the uniform-motion model predicts 100 m. If the learner can explain the unit cancellation (m/s × s = m), the conversion is meaningful rather than a memorised calculator button.

4. Convert km/h to m/s 4

Question. An imaginary vehicle has a stated speed of 45 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 45×1000/3600 = 45/3.6 = 12.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 12.5 m/s by 3.6 to recover 45 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

Transfer. At 45 km/h for ten seconds, the uniform-motion model predicts 125 m. If the learner can explain the unit cancellation (m/s × s = m), the conversion is meaningful rather than a memorised calculator button.

5. Convert km/h to m/s 5

Question. An imaginary vehicle has a stated speed of 54 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 54×1000/3600 = 54/3.6 = 15 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 15 m/s by 3.6 to recover 54 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

Transfer. At 54 km/h for ten seconds, the uniform-motion model predicts 150 m. If the learner can explain the unit cancellation (m/s × s = m), the conversion is meaningful rather than a memorised calculator button.

6. Convert km/h to m/s 6

Question. An imaginary vehicle has a stated speed of 63 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 63×1000/3600 = 63/3.6 = 17.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 17.5 m/s by 3.6 to recover 63 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

Transfer. At 63 km/h for ten seconds, the uniform-motion model predicts 175 m. If the learner can explain the unit cancellation (m/s × s = m), the conversion is meaningful rather than a memorised calculator button.

7. Convert km/h to m/s 7

Question. An imaginary vehicle has a stated speed of 72 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 72×1000/3600 = 72/3.6 = 20 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 20 m/s by 3.6 to recover 72 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

Transfer. At 72 km/h for ten seconds, the uniform-motion model predicts 200 m. If the learner can explain the unit cancellation (m/s × s = m), the conversion is meaningful rather than a memorised calculator button.

8. Convert km/h to m/s 8

Question. An imaginary vehicle has a stated speed of 81 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 81×1000/3600 = 81/3.6 = 22.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 22.5 m/s by 3.6 to recover 81 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

Transfer. At 81 km/h for ten seconds, the uniform-motion model predicts 225 m. If the learner can explain the unit cancellation (m/s × s = m), the conversion is meaningful rather than a memorised calculator button.

9. Convert km/h to m/s 9

Question. An imaginary vehicle has a stated speed of 90 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 90×1000/3600 = 90/3.6 = 25 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 25 m/s by 3.6 to recover 90 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

Transfer. At 90 km/h for ten seconds, the uniform-motion model predicts 250 m. If the learner can explain the unit cancellation (m/s × s = m), the conversion is meaningful rather than a memorised calculator button.

10. Convert km/h to m/s 10

Question. An imaginary vehicle has a stated speed of 108 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 108×1000/3600 = 108/3.6 = 30 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 30 m/s by 3.6 to recover 108 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

Transfer. At 108 km/h for ten seconds, the uniform-motion model predicts 300 m. If the learner can explain the unit cancellation (m/s × s = m), the conversion is meaningful rather than a memorised calculator button.

11. Convert km/h to m/s 11

Question. An imaginary vehicle has a stated speed of 144 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 144×1000/3600 = 144/3.6 = 40 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 40 m/s by 3.6 to recover 144 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

Transfer. At 144 km/h for ten seconds, the uniform-motion model predicts 400 m. If the learner can explain the unit cancellation (m/s × s = m), the conversion is meaningful rather than a memorised calculator button.

12. Convert km/h to m/s 12

Question. An imaginary vehicle has a stated speed of 9 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 9×1000/3600 = 9/3.6 = 2.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 2.5 m/s by 3.6 to recover 9 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

Transfer. At 9 km/h for ten seconds, the uniform-motion model predicts 25 m. If the learner can explain the unit cancellation (m/s × s = m), the conversion is meaningful rather than a memorised calculator button.

13. Convert m/s to km/h 1

Question. A fictional moving object travels at 2.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 2.5×3.6 = 9 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 9 km/h by 3.6 to recover 2.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 2.5 m/s gives 50 metres. Compute the same distance using 9 km/h and time 20/3600 hours; the two methods must agree.

14. Convert m/s to km/h 2

Question. A fictional moving object travels at 5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 5×3.6 = 18 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 18 km/h by 3.6 to recover 5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 5 m/s gives 100 metres. Compute the same distance using 18 km/h and time 20/3600 hours; the two methods must agree.

15. Convert m/s to km/h 3

Question. A fictional moving object travels at 7.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 7.5×3.6 = 27 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 27 km/h by 3.6 to recover 7.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 7.5 m/s gives 150 metres. Compute the same distance using 27 km/h and time 20/3600 hours; the two methods must agree.

16. Convert m/s to km/h 4

Question. A fictional moving object travels at 10 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 10×3.6 = 36 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 36 km/h by 3.6 to recover 10 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 10 m/s gives 200 metres. Compute the same distance using 36 km/h and time 20/3600 hours; the two methods must agree.

17. Convert m/s to km/h 5

Question. A fictional moving object travels at 12.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 12.5×3.6 = 45 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 45 km/h by 3.6 to recover 12.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 12.5 m/s gives 250 metres. Compute the same distance using 45 km/h and time 20/3600 hours; the two methods must agree.

18. Convert m/s to km/h 6

Question. A fictional moving object travels at 15 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 15×3.6 = 54 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 54 km/h by 3.6 to recover 15 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 15 m/s gives 300 metres. Compute the same distance using 54 km/h and time 20/3600 hours; the two methods must agree.

19. Convert m/s to km/h 7

Question. A fictional moving object travels at 17.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 17.5×3.6 = 63 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 63 km/h by 3.6 to recover 17.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 17.5 m/s gives 350 metres. Compute the same distance using 63 km/h and time 20/3600 hours; the two methods must agree.

20. Convert m/s to km/h 8

Question. A fictional moving object travels at 20 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 20×3.6 = 72 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 72 km/h by 3.6 to recover 20 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 20 m/s gives 400 metres. Compute the same distance using 72 km/h and time 20/3600 hours; the two methods must agree.

21. Convert m/s to km/h 9

Question. A fictional moving object travels at 22.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 22.5×3.6 = 81 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 81 km/h by 3.6 to recover 22.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 22.5 m/s gives 450 metres. Compute the same distance using 81 km/h and time 20/3600 hours; the two methods must agree.

22. Convert m/s to km/h 10

Question. A fictional moving object travels at 25 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 25×3.6 = 90 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 90 km/h by 3.6 to recover 25 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 25 m/s gives 500 metres. Compute the same distance using 90 km/h and time 20/3600 hours; the two methods must agree.

23. Find average speed with minutes 1

Question. A hypothetical journey covers 24 km in 30 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 30 min to 0.5 h. Average speed is distance ÷ time = 24 ÷ (30/60) = 48 km/h.

First wrong step to avoid. Dividing 24 by 30 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 0.5 h reproduces 24 km, up to any displayed rounding. The units km/h × h simplify to km.

Transfer. What if the distance were doubled while the elapsed time stayed 30 minutes? The average speed would double. What if the time doubled and distance stayed 24 km? Average speed would halve. Explain these as relationships, not fresh formula memorisation.

24. Find average speed with minutes 2

Question. A hypothetical journey covers 45 km in 45 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 45 min to 0.75 h. Average speed is distance ÷ time = 45 ÷ (45/60) = 60 km/h.

First wrong step to avoid. Dividing 45 by 45 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 60 km/h multiplied by 0.75 h reproduces 45 km, up to any displayed rounding. The units km/h × h simplify to km.

Transfer. What if the distance were doubled while the elapsed time stayed 45 minutes? The average speed would double. What if the time doubled and distance stayed 45 km? Average speed would halve. Explain these as relationships, not fresh formula memorisation.

25. Find average speed with minutes 3

Question. A hypothetical journey covers 60 km in 75 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 75 min to 1.25 h. Average speed is distance ÷ time = 60 ÷ (75/60) = 48 km/h.

First wrong step to avoid. Dividing 60 by 75 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 1.25 h reproduces 60 km, up to any displayed rounding. The units km/h × h simplify to km.

Transfer. What if the distance were doubled while the elapsed time stayed 75 minutes? The average speed would double. What if the time doubled and distance stayed 60 km? Average speed would halve. Explain these as relationships, not fresh formula memorisation.

26. Find average speed with minutes 4

Question. A hypothetical journey covers 27 km in 20 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 20 min to 0.33333 h. Average speed is distance ÷ time = 27 ÷ (20/60) = 81 km/h.

First wrong step to avoid. Dividing 27 by 20 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 81 km/h multiplied by 0.33333 h reproduces 27 km, up to any displayed rounding. The units km/h × h simplify to km.

Transfer. What if the distance were doubled while the elapsed time stayed 20 minutes? The average speed would double. What if the time doubled and distance stayed 27 km? Average speed would halve. Explain these as relationships, not fresh formula memorisation.

27. Find average speed with minutes 5

Question. A hypothetical journey covers 36 km in 50 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 50 min to 0.83333 h. Average speed is distance ÷ time = 36 ÷ (50/60) = 43.2 km/h.

First wrong step to avoid. Dividing 36 by 50 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 43.2 km/h multiplied by 0.83333 h reproduces 36 km, up to any displayed rounding. The units km/h × h simplify to km.

Transfer. What if the distance were doubled while the elapsed time stayed 50 minutes? The average speed would double. What if the time doubled and distance stayed 36 km? Average speed would halve. Explain these as relationships, not fresh formula memorisation.

28. Find average speed with minutes 6

Question. A hypothetical journey covers 105 km in 90 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 90 min to 1.5 h. Average speed is distance ÷ time = 105 ÷ (90/60) = 70 km/h.

First wrong step to avoid. Dividing 105 by 90 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 70 km/h multiplied by 1.5 h reproduces 105 km, up to any displayed rounding. The units km/h × h simplify to km.

Transfer. What if the distance were doubled while the elapsed time stayed 90 minutes? The average speed would double. What if the time doubled and distance stayed 105 km? Average speed would halve. Explain these as relationships, not fresh formula memorisation.

29. Find average speed with minutes 7

Question. A hypothetical journey covers 12 km in 15 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 15 min to 0.25 h. Average speed is distance ÷ time = 12 ÷ (15/60) = 48 km/h.

First wrong step to avoid. Dividing 12 by 15 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 0.25 h reproduces 12 km, up to any displayed rounding. The units km/h × h simplify to km.

Transfer. What if the distance were doubled while the elapsed time stayed 15 minutes? The average speed would double. What if the time doubled and distance stayed 12 km? Average speed would halve. Explain these as relationships, not fresh formula memorisation.

30. Find average speed with minutes 8

Question. A hypothetical journey covers 96 km in 80 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 80 min to 1.3333 h. Average speed is distance ÷ time = 96 ÷ (80/60) = 72 km/h.

First wrong step to avoid. Dividing 96 by 80 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 72 km/h multiplied by 1.3333 h reproduces 96 km, up to any displayed rounding. The units km/h × h simplify to km.

Transfer. What if the distance were doubled while the elapsed time stayed 80 minutes? The average speed would double. What if the time doubled and distance stayed 96 km? Average speed would halve. Explain these as relationships, not fresh formula memorisation.

31. Find average speed with minutes 9

Question. A hypothetical journey covers 14 km in 35 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 35 min to 0.58333 h. Average speed is distance ÷ time = 14 ÷ (35/60) = 24 km/h.

First wrong step to avoid. Dividing 14 by 35 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 24 km/h multiplied by 0.58333 h reproduces 14 km, up to any displayed rounding. The units km/h × h simplify to km.

Transfer. What if the distance were doubled while the elapsed time stayed 35 minutes? The average speed would double. What if the time doubled and distance stayed 14 km? Average speed would halve. Explain these as relationships, not fresh formula memorisation.

32. Find average speed with minutes 10

Question. A hypothetical journey covers 33 km in 22 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 22 min to 0.36667 h. Average speed is distance ÷ time = 33 ÷ (22/60) = 90 km/h.

First wrong step to avoid. Dividing 33 by 22 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 90 km/h multiplied by 0.36667 h reproduces 33 km, up to any displayed rounding. The units km/h × h simplify to km.

Transfer. What if the distance were doubled while the elapsed time stayed 22 minutes? The average speed would double. What if the time doubled and distance stayed 33 km? Average speed would halve. Explain these as relationships, not fresh formula memorisation.

33. Find average speed with minutes 11

Question. A hypothetical journey covers 75 km in 50 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 50 min to 0.83333 h. Average speed is distance ÷ time = 75 ÷ (50/60) = 90 km/h.

First wrong step to avoid. Dividing 75 by 50 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 90 km/h multiplied by 0.83333 h reproduces 75 km, up to any displayed rounding. The units km/h × h simplify to km.

Transfer. What if the distance were doubled while the elapsed time stayed 50 minutes? The average speed would double. What if the time doubled and distance stayed 75 km? Average speed would halve. Explain these as relationships, not fresh formula memorisation.

34. Find average speed with minutes 12

Question. A hypothetical journey covers 126 km in 105 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 105 min to 1.75 h. Average speed is distance ÷ time = 126 ÷ (105/60) = 72 km/h.

First wrong step to avoid. Dividing 126 by 105 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 72 km/h multiplied by 1.75 h reproduces 126 km, up to any displayed rounding. The units km/h × h simplify to km.

Transfer. What if the distance were doubled while the elapsed time stayed 105 minutes? The average speed would double. What if the time doubled and distance stayed 126 km? Average speed would halve. Explain these as relationships, not fresh formula memorisation.

35. Use total distance and total time 1

Question. On an invented two-stage journey, stage one covers 60 km in 1 h, and stage two covers 60 km in 2 h. Find overall average speed.

Work it through. Total distance is 60+60=120 km. Total elapsed time is 1+2=3 h. Divide totals: 120/3=40 km/h.

First wrong step to avoid. Taking the ordinary mean of the two stage speeds without considering how long each stage lasted can be misleading. The journey average is defined by total distance divided by total time.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 30 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

36. Use total distance and total time 2

Question. On an invented two-stage journey, stage one covers 30 km in 0.5 h, and stage two covers 90 km in 1.5 h. Find overall average speed.

Work it through. Total distance is 30+90=120 km. Total elapsed time is 0.5+1.5=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

37. Use total distance and total time 3

Question. On an invented two-stage journey, stage one covers 80 km in 2 h, and stage two covers 40 km in 0.5 h. Find overall average speed.

Work it through. Total distance is 80+40=120 km. Total elapsed time is 2+0.5=2.5 h. Divide totals: 120/2.5=48 km/h.

Check. 48×2.5≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 40 and 80 km/h. Compare them with the overall 48. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

38. Use total distance and total time 4

Question. On an invented two-stage journey, stage one covers 70 km in 1 h, and stage two covers 30 km in 1.5 h. Find overall average speed.

Work it through. Total distance is 70+30=100 km. Total elapsed time is 1+1.5=2.5 h. Divide totals: 100/2.5=40 km/h.

Check. 40×2.5≈100 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 70 and 20 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

39. Use total distance and total time 5

Question. On an invented two-stage journey, stage one covers 45 km in 0.75 h, and stage two covers 75 km in 1.25 h. Find overall average speed.

Work it through. Total distance is 45+75=120 km. Total elapsed time is 0.75+1.25=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

40. Use total distance and total time 6

Question. On an invented two-stage journey, stage one covers 20 km in 0.5 h, and stage two covers 100 km in 2.5 h. Find overall average speed.

Work it through. Total distance is 20+100=120 km. Total elapsed time is 0.5+2.5=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 40 and 40 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

41. Use total distance and total time 7

Question. On an invented two-stage journey, stage one covers 48 km in 1 h, and stage two covers 72 km in 2 h. Find overall average speed.

Work it through. Total distance is 48+72=120 km. Total elapsed time is 1+2=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 48 and 36 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

42. Use total distance and total time 8

Question. On an invented two-stage journey, stage one covers 50 km in 1.25 h, and stage two covers 90 km in 1.75 h. Find overall average speed.

Work it through. Total distance is 50+90=140 km. Total elapsed time is 1.25+1.75=3 h. Divide totals: 140/3=46.667 km/h (rounded as displayed).

Check. 46.667×3≈140 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 40 and 51.429 km/h. Compare them with the overall 46.667. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

43. Use total distance and total time 9

Question. On an invented two-stage journey, stage one covers 90 km in 1.5 h, and stage two covers 30 km in 0.5 h. Find overall average speed.

Work it through. Total distance is 90+30=120 km. Total elapsed time is 1.5+0.5=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

44. Use total distance and total time 10

Question. On an invented two-stage journey, stage one covers 36 km in 0.75 h, and stage two covers 84 km in 1.75 h. Find overall average speed.

Work it through. Total distance is 36+84=120 km. Total elapsed time is 0.75+1.75=2.5 h. Divide totals: 120/2.5=48 km/h.

Check. 48×2.5≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 48 and 48 km/h. Compare them with the overall 48. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

45. Use total distance and total time 11

Question. On an invented two-stage journey, stage one covers 65 km in 1.3 h, and stage two covers 35 km in 0.7 h. Find overall average speed.

Work it through. Total distance is 65+35=100 km. Total elapsed time is 1.3+0.7=2 h. Divide totals: 100/2=50 km/h.

Check. 50×2≈100 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 50 and 50 km/h. Compare them with the overall 50. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

46. Reason about a rate or elapsed time 1

Question. An office printer makes 144 pages in 12 minutes. What is its average pages per minute?

Work it through. 144 ÷ 12 = 12 pages/min.

First wrong step to avoid. Reading 12 as minutes per page, which reverses the rate.

Check. At this rate 5 minutes produces 60 pages.

Transfer. Rewrite the problem with a different unit. For a time answer, convert minutes to hours or vice versa; for a speed answer, state the rate in a different valid unit when practical. Explain why the number changes but the represented quantity does not. Where the story involves stops, name explicitly whether they belong in the requested elapsed interval.

47. Reason about a rate or elapsed time 2

Question. A tap adds 48 litres in eight minutes. What is its average flow?

Work it through. 48 ÷ 8 = 6 L/min.

First wrong step to avoid. Writing 6 min/L rather than litres per minute.

Check. Check 6 L/min × 8 min = 48 L.

48. Reason about a rate or elapsed time 3

Question. A machine makes 84 labels in seven minutes. How long for 132 labels at constant rate?

Work it through. Its rate is 84/7=12 labels/min. Required time is 132/12 = 11 minutes.

First wrong step to avoid. Multiplying labels by the rate rather than dividing to find time.

Check. 12 labels/min × 11 min = 132 labels.

49. Reason about a rate or elapsed time 4

Question. A student reads 24 pages in 30 minutes at a constant pace. What is the page rate?

Work it through. Rate=24/30=0.8 pages/min, or 48 pages/hour.

First wrong step to avoid. Reporting 1.25 pages/min, which is the minutes per page instead.

Check. Check 0.8×30=24 pages.

50. Reason about a rate or elapsed time 5

Question. A fictional pump moves 90 L in six minutes. How long for 225 L at the same rate?

Work it through. Rate=90/6=15 L/min. Time=225/15=15 minutes.

First wrong step to avoid. Using 225×15 and obtaining an amount with incorrect units.

Check. 15 L/min × 15 min = 225 L.

51. Reason about a rate or elapsed time 6

Question. Convert 2.5 hours to hours and minutes.

Work it through. 0.5 h is thirty minutes, so 2 h 30 min.

First wrong step to avoid. Reading 2.5 as two hours five minutes.

Check. 2 + 30/60 = 2.5 hours.

52. Reason about a rate or elapsed time 7

Question. Convert one hour 12 minutes to decimal hours.

Work it through. 12/60 = 0.2 hour, so total is 1.2 hours.

First wrong step to avoid. Writing 1.12 hours by treating minutes as decimal hundredths.

Check. 1.2×60=72 minutes.

53. Reason about a rate or elapsed time 8

Question. A car covers 150 km at uniform 50 km/h. Find duration.

Work it through. Time=distance/speed=150/50=3 h.

First wrong step to avoid. Multiplying speed and distance to find time.

Check. 50 km/h × 3 h = 150 km.

54. Reason about a rate or elapsed time 9

Question. A cyclist travels at constant 18 km/h for 40 minutes. Find distance.

Work it through. 40 minutes is 2/3 hour. Distance=18×(2/3)=12 km.

First wrong step to avoid. Using 18×40 as if minutes were hours.

Check. 12 km/(2/3 h)=18 km/h.

55. Reason about a rate or elapsed time 10

Question. A journey covers 30 km at 60 km/h, then includes a 30-minute stop. Find average speed for the full elapsed hour.

Work it through. Moving time is 0.5 h and stopped time is 0.5 h. Total elapsed is one hour, so average speed=30 km/h.

First wrong step to avoid. Ignoring stationary time and reporting 60 km/h for the whole elapsed interval.

Check. 30 km÷1 h=30 km/h; be clear about what the question calls elapsed time.

56. Reason about a rate or elapsed time 11

Question. A walker covers 3 km in 30 minutes and then rests 15 minutes. Find average speed across the entire interval.

Work it through. Distance=3 km; elapsed time=45 min=0.75 h, so speed=3/0.75=4 km/h.

First wrong step to avoid. Using only walking time when the problem includes the rest in the requested interval.

Check. 3 km÷0.75 h=4 km/h.

57. Reason about a rate or elapsed time 12

Question. Outward distance 60 km at 60 km/h, return distance 60 km at 30 km/h. Find full-trip average speed.

Work it through. Outward time=1 h, return time=2 h, total distance=120 km and total time=3 h, so average=40 km/h.

First wrong step to avoid. Averaging 60 and 30 to 45 km/h is wrong because journey times differ.

Check. 40×3=120 km; this is the unequal-time equal-distance trap.

58. Reason about a rate or elapsed time 13

Question. For the same fixed 180-km journey, compare 60 km/h with 90 km/h travel times.

Work it through. At 60 km/h, time=180/60=3 h. At 90 km/h, time=180/90=2 h. Faster travel saves one hour in the ideal constant-speed model.

First wrong step to avoid. Calling the time saving 30 minutes because the speed rose by 30 km/h.

Check. Check both speed×time products equal 180 km.

59. Reason about a rate or elapsed time 14

Question. A hypothetical conveyor carries 360 parts in 15 minutes. Find parts per hour.

Work it through. Rate=360/15=24 parts/min, or 24×60=1440 parts/hour.

First wrong step to avoid. Dividing by 60 when converting a per-minute count into a per-hour count.

Check. 1440/60=24 parts/min.

60. Reason about a rate or elapsed time 15

Question. A tank holds 240 L and fills at a constant 20 L/min. How long to fill from empty?

Work it through. Time=240/20=12 minutes.

First wrong step to avoid. Multiplying 240×20, which has units L²/min.

Check. 20 L/min × 12 min = 240 L.

61. Reason about a rate or elapsed time 16

Question. A vehicle travels at 5 m/s for 12 seconds. Find its distance.

Work it through. Distance=5×12=60 m.

First wrong step to avoid. Giving 60 m/s when the requested quantity is distance.

Check. 60m/12s=5m/s.

62. Reason about a rate or elapsed time 17

Question. A student says 72 km/h equals 72 m/s. Explain the error.

Work it through. The numerical value changes under unit conversion: 72 km/h ÷ 3.6 = 20 m/s.

First wrong step to avoid. Assuming two units of speed use the same number.

Check. 20 m/s is 72 km/h because 20×3.6=72.

63. Reason about a rate or elapsed time 18

Question. A 120-km trip has a 90-minute moving period and a 30-minute stop. What is average speed including stop?

Work it through. Total elapsed=120 min=2 h, so average speed=60 km/h.

First wrong step to avoid. Dividing by 1.5 h instead of the full two hours requested.

Check. 60 km/h×2 h=120 km.

64. Reason about a rate or elapsed time 19

Question. A rate is 36 km/h. How far is travelled in 15 minutes at constant speed?

Work it through. 15 min=0.25 h; distance=36×0.25=9 km.

First wrong step to avoid. Treating fifteen minutes as 0.15 hour.

Check. 9 km/0.25 h=36 km/h.

65. Reason about a rate or elapsed time 20

Question. Two journeys have equal distance but different average speeds. Which one takes longer?

Work it through. At fixed distance, time=distance/speed, so the one with lower average speed takes longer, assuming the same definition of elapsed time.

First wrong step to avoid. Concluding that a larger km/h number means larger hours.

Check. Use 100 km at 50 km/h (2 h) and 100 km at 100 km/h (1 h).

66. Reason about a rate or elapsed time 21

Question. A numerical answer of 3 may represent different units. How can a pupil decide?

Work it through. Read the requested quantity and analyse units: km÷(km/h) gives hours; km÷h gives km/h; km/h×h gives kilometres.

First wrong step to avoid. Writing only 3 without units because the arithmetic looks tidy.

Check. Show the cancellation in each case, then state the correct noun.

Five typical speed mistakes and their repairs

error1

A pupil divides 36 km by 45 minutes and calls the answer 0.8 km/h. That calculation is 0.8 kilometres per minute, not per hour. Convert 45 minutes to 0.75 hour and divide 36/0.75=48 km/h. Alternatively multiply 0.8 km/min by 60 min/h to get 48 km/h. Both should agree.

error2

A child multiplies 72 km/h by 3.6 and gets 259.2 m/s. Ask whether moving from kilometres per hour to metres per second should produce a number near twenty or near 260. Derive the factor using 1000 m per km and 3600 s per hour; the correct answer is 20 m/s. Round-trip conversion recovers 72.

error3

A learner reports (60+30)/2=45 km/h for equal 60-km legs. But the faster leg takes one hour and the slower leg takes two, so the total distance/time average is 120/3=40 km/h. The correction is to name the two totals. The arithmetic mean of stage speeds happens to be appropriate only under suitable equal-time conditions, not simply because there are two stages.

error4

A pupil includes a journey’s distance but leaves out a stated rest break even though the question says ‘for the full elapsed interval’. Draw a timeline, mark movement and rest, and add both durations. There is no need to invent motion during the stop; the distance remains unchanged while the elapsed time grows.

error5

One student reports 15 km after being asked for speed, or 15 km/h after being asked for time. Write distance (km), speed (km/h) and time (h) beside the three quantities and cancel units symbolically. The correct numerical method should leave the requested unit. A label error often signals that the relationship itself was not understood.

How an illustrative three-pupil tutorial might work

The immutable eduKateSG Clementi three-pupil Mathematics reference describes 90-minute lessons near Sixth Avenue MRT. For a Secondary 2 G1 rates lesson, the tutor could separately observe one pupil’s unit conversion, another’s two-stage totals and a third’s interpretation of a rest break. The programme description is not a guarantee of a current opening; confirm actual matching, timing and venue.

First 10 minutes: retrieve metric and time conversions without a calculator.
Next 20 minutes: derive the speed formulas from units and convert both km/h and m/s.
Next 25 minutes: individual mixed speed and time problems with first-line feedback.
Next 15 minutes: compare stage-speed arithmetic with whole-trip average speed.
Next 10 minutes: unseen mixed rates including print output or liquid flow.
Final 10 minutes: recheck units and plan short retrieval practice.

Five short home sessions

Monday: derive the 3.6 conversion factor from 1000 and 3600, then convert six speeds both ways.
Tuesday: convert minutes and mixed hours into decimal hours and back.
Wednesday: solve two questions each for distance, speed and duration.
Thursday: find total distance and elapsed time for two-stage journeys; include one with a stop.
Friday: practise non-travel rates, then re-solve the week’s first mistaken calculation without viewing the answer.

G1 subject level and the published 2027 SEC syllabus

Frequently asked questions

faq1

Because one kilometre is 1000 metres and one hour is 3600 seconds; 1000/3600=1/3.6.

faq2

faq3

It counts when the question defines total elapsed journey time to include that stop. Read the requested interval carefully.

faq4

The stages may have unequal durations or distances. The whole-trip average comes from total distance and total time; an unweighted mean can be wrong.

faq5

The underlying concept is the same: output divided by time. Preserve the actual units such as pages/min or L/min.

faq6

Yes. It is explicitly listed in the MOE Secondary Two G1 N4 content. School assessment dates and emphasis vary.

Official references and reader note

One-minute speed diagnostic
Why the 3.6 factor works
Average speed across stages and stops
50-plus original speed clinics
First-error diagnosis
Three-pupil tutorial model
A five-day revision plan
FAQs
Official sources

A 60-second diagnostic

Speed conversion is a ratio of units

one

two

three

Average speed depends on both totals

total

rest

direction

Original rate, speed and unit-conversion clinics

1. Convert km/h to m/s 1

Question. An imaginary vehicle has a stated speed of 18 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 18×1000/3600 = 18/3.6 = 5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 5 m/s by 3.6 to recover 18 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

2. Convert km/h to m/s 2

Question. An imaginary vehicle has a stated speed of 27 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 27×1000/3600 = 27/3.6 = 7.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 7.5 m/s by 3.6 to recover 27 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

3. Convert km/h to m/s 3

Question. An imaginary vehicle has a stated speed of 36 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 36×1000/3600 = 36/3.6 = 10 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 10 m/s by 3.6 to recover 36 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

4. Convert km/h to m/s 4

Question. An imaginary vehicle has a stated speed of 45 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 45×1000/3600 = 45/3.6 = 12.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 12.5 m/s by 3.6 to recover 45 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

5. Convert km/h to m/s 5

Question. An imaginary vehicle has a stated speed of 54 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 54×1000/3600 = 54/3.6 = 15 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 15 m/s by 3.6 to recover 54 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

6. Convert km/h to m/s 6

Question. An imaginary vehicle has a stated speed of 63 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 63×1000/3600 = 63/3.6 = 17.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 17.5 m/s by 3.6 to recover 63 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

7. Convert km/h to m/s 7

Question. An imaginary vehicle has a stated speed of 72 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 72×1000/3600 = 72/3.6 = 20 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 20 m/s by 3.6 to recover 72 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

8. Convert km/h to m/s 8

Question. An imaginary vehicle has a stated speed of 81 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 81×1000/3600 = 81/3.6 = 22.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 22.5 m/s by 3.6 to recover 81 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

9. Convert km/h to m/s 9

Question. An imaginary vehicle has a stated speed of 90 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 90×1000/3600 = 90/3.6 = 25 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 25 m/s by 3.6 to recover 90 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

10. Convert km/h to m/s 10

Question. An imaginary vehicle has a stated speed of 108 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 108×1000/3600 = 108/3.6 = 30 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 30 m/s by 3.6 to recover 108 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

11. Convert km/h to m/s 11

Question. An imaginary vehicle has a stated speed of 144 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 144×1000/3600 = 144/3.6 = 40 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 40 m/s by 3.6 to recover 144 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

12. Convert km/h to m/s 12

Question. An imaginary vehicle has a stated speed of 9 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 9×1000/3600 = 9/3.6 = 2.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 2.5 m/s by 3.6 to recover 9 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

13. Convert m/s to km/h 1

Question. A fictional moving object travels at 2.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 2.5×3.6 = 9 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 9 km/h by 3.6 to recover 2.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 2.5 m/s gives 50 metres. Compute the same distance using 9 km/h and time 20/3600 hours; the two methods must agree.

14. Convert m/s to km/h 2

Question. A fictional moving object travels at 5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 5×3.6 = 18 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 18 km/h by 3.6 to recover 5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 5 m/s gives 100 metres. Compute the same distance using 18 km/h and time 20/3600 hours; the two methods must agree.

15. Convert m/s to km/h 3

Question. A fictional moving object travels at 7.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 7.5×3.6 = 27 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 27 km/h by 3.6 to recover 7.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 7.5 m/s gives 150 metres. Compute the same distance using 27 km/h and time 20/3600 hours; the two methods must agree.

16. Convert m/s to km/h 4

Question. A fictional moving object travels at 10 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 10×3.6 = 36 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 36 km/h by 3.6 to recover 10 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 10 m/s gives 200 metres. Compute the same distance using 36 km/h and time 20/3600 hours; the two methods must agree.

17. Convert m/s to km/h 5

Question. A fictional moving object travels at 12.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 12.5×3.6 = 45 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 45 km/h by 3.6 to recover 12.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 12.5 m/s gives 250 metres. Compute the same distance using 45 km/h and time 20/3600 hours; the two methods must agree.

18. Convert m/s to km/h 6

Question. A fictional moving object travels at 15 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 15×3.6 = 54 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 54 km/h by 3.6 to recover 15 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 15 m/s gives 300 metres. Compute the same distance using 54 km/h and time 20/3600 hours; the two methods must agree.

19. Convert m/s to km/h 7

Question. A fictional moving object travels at 17.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 17.5×3.6 = 63 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 63 km/h by 3.6 to recover 17.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 17.5 m/s gives 350 metres. Compute the same distance using 63 km/h and time 20/3600 hours; the two methods must agree.

20. Convert m/s to km/h 8

Question. A fictional moving object travels at 20 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 20×3.6 = 72 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 72 km/h by 3.6 to recover 20 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 20 m/s gives 400 metres. Compute the same distance using 72 km/h and time 20/3600 hours; the two methods must agree.

21. Convert m/s to km/h 9

Question. A fictional moving object travels at 22.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 22.5×3.6 = 81 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 81 km/h by 3.6 to recover 22.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 22.5 m/s gives 450 metres. Compute the same distance using 81 km/h and time 20/3600 hours; the two methods must agree.

22. Convert m/s to km/h 10

Question. A fictional moving object travels at 25 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 25×3.6 = 90 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 90 km/h by 3.6 to recover 25 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 25 m/s gives 500 metres. Compute the same distance using 90 km/h and time 20/3600 hours; the two methods must agree.

23. Find average speed with minutes 1

Question. A hypothetical journey covers 24 km in 30 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 30 min to 0.5 h. Average speed is distance ÷ time = 24 ÷ (30/60) = 48 km/h.

First wrong step to avoid. Dividing 24 by 30 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 0.5 h reproduces 24 km, up to any displayed rounding. The units km/h × h simplify to km.

24. Find average speed with minutes 2

Question. A hypothetical journey covers 45 km in 45 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 45 min to 0.75 h. Average speed is distance ÷ time = 45 ÷ (45/60) = 60 km/h.

First wrong step to avoid. Dividing 45 by 45 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 60 km/h multiplied by 0.75 h reproduces 45 km, up to any displayed rounding. The units km/h × h simplify to km.

25. Find average speed with minutes 3

Question. A hypothetical journey covers 60 km in 75 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 75 min to 1.25 h. Average speed is distance ÷ time = 60 ÷ (75/60) = 48 km/h.

First wrong step to avoid. Dividing 60 by 75 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 1.25 h reproduces 60 km, up to any displayed rounding. The units km/h × h simplify to km.

26. Find average speed with minutes 4

Question. A hypothetical journey covers 27 km in 20 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 20 min to 0.33333 h. Average speed is distance ÷ time = 27 ÷ (20/60) = 81 km/h.

First wrong step to avoid. Dividing 27 by 20 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 81 km/h multiplied by 0.33333 h reproduces 27 km, up to any displayed rounding. The units km/h × h simplify to km.

27. Find average speed with minutes 5

Question. A hypothetical journey covers 36 km in 50 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 50 min to 0.83333 h. Average speed is distance ÷ time = 36 ÷ (50/60) = 43.2 km/h.

First wrong step to avoid. Dividing 36 by 50 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 43.2 km/h multiplied by 0.83333 h reproduces 36 km, up to any displayed rounding. The units km/h × h simplify to km.

28. Find average speed with minutes 6

Question. A hypothetical journey covers 105 km in 90 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 90 min to 1.5 h. Average speed is distance ÷ time = 105 ÷ (90/60) = 70 km/h.

First wrong step to avoid. Dividing 105 by 90 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 70 km/h multiplied by 1.5 h reproduces 105 km, up to any displayed rounding. The units km/h × h simplify to km.

29. Find average speed with minutes 7

Question. A hypothetical journey covers 12 km in 15 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 15 min to 0.25 h. Average speed is distance ÷ time = 12 ÷ (15/60) = 48 km/h.

First wrong step to avoid. Dividing 12 by 15 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 0.25 h reproduces 12 km, up to any displayed rounding. The units km/h × h simplify to km.

30. Find average speed with minutes 8

Question. A hypothetical journey covers 96 km in 80 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 80 min to 1.3333 h. Average speed is distance ÷ time = 96 ÷ (80/60) = 72 km/h.

First wrong step to avoid. Dividing 96 by 80 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 72 km/h multiplied by 1.3333 h reproduces 96 km, up to any displayed rounding. The units km/h × h simplify to km.

31. Find average speed with minutes 9

Question. A hypothetical journey covers 14 km in 35 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 35 min to 0.58333 h. Average speed is distance ÷ time = 14 ÷ (35/60) = 24 km/h.

First wrong step to avoid. Dividing 14 by 35 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 24 km/h multiplied by 0.58333 h reproduces 14 km, up to any displayed rounding. The units km/h × h simplify to km.

32. Find average speed with minutes 10

Question. A hypothetical journey covers 33 km in 22 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 22 min to 0.36667 h. Average speed is distance ÷ time = 33 ÷ (22/60) = 90 km/h.

First wrong step to avoid. Dividing 33 by 22 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 90 km/h multiplied by 0.36667 h reproduces 33 km, up to any displayed rounding. The units km/h × h simplify to km.

33. Find average speed with minutes 11

Question. A hypothetical journey covers 75 km in 50 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 50 min to 0.83333 h. Average speed is distance ÷ time = 75 ÷ (50/60) = 90 km/h.

First wrong step to avoid. Dividing 75 by 50 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 90 km/h multiplied by 0.83333 h reproduces 75 km, up to any displayed rounding. The units km/h × h simplify to km.

34. Find average speed with minutes 12

Question. A hypothetical journey covers 126 km in 105 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 105 min to 1.75 h. Average speed is distance ÷ time = 126 ÷ (105/60) = 72 km/h.

First wrong step to avoid. Dividing 126 by 105 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 72 km/h multiplied by 1.75 h reproduces 126 km, up to any displayed rounding. The units km/h × h simplify to km.

35. Use total distance and total time 1

Question. On an invented two-stage journey, stage one covers 60 km in 1 h, and stage two covers 60 km in 2 h. Find overall average speed.

Work it through. Total distance is 60+60=120 km. Total elapsed time is 1+2=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 30 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

36. Use total distance and total time 2

Question. On an invented two-stage journey, stage one covers 30 km in 0.5 h, and stage two covers 90 km in 1.5 h. Find overall average speed.

Work it through. Total distance is 30+90=120 km. Total elapsed time is 0.5+1.5=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

37. Use total distance and total time 3

Question. On an invented two-stage journey, stage one covers 80 km in 2 h, and stage two covers 40 km in 0.5 h. Find overall average speed.

Work it through. Total distance is 80+40=120 km. Total elapsed time is 2+0.5=2.5 h. Divide totals: 120/2.5=48 km/h.

Check. 48×2.5≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 40 and 80 km/h. Compare them with the overall 48. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

38. Use total distance and total time 4

Question. On an invented two-stage journey, stage one covers 70 km in 1 h, and stage two covers 30 km in 1.5 h. Find overall average speed.

Work it through. Total distance is 70+30=100 km. Total elapsed time is 1+1.5=2.5 h. Divide totals: 100/2.5=40 km/h.

Check. 40×2.5≈100 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 70 and 20 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

39. Use total distance and total time 5

Question. On an invented two-stage journey, stage one covers 45 km in 0.75 h, and stage two covers 75 km in 1.25 h. Find overall average speed.

Work it through. Total distance is 45+75=120 km. Total elapsed time is 0.75+1.25=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

40. Use total distance and total time 6

Question. On an invented two-stage journey, stage one covers 20 km in 0.5 h, and stage two covers 100 km in 2.5 h. Find overall average speed.

Work it through. Total distance is 20+100=120 km. Total elapsed time is 0.5+2.5=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 40 and 40 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

41. Use total distance and total time 7

Question. On an invented two-stage journey, stage one covers 48 km in 1 h, and stage two covers 72 km in 2 h. Find overall average speed.

Work it through. Total distance is 48+72=120 km. Total elapsed time is 1+2=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 48 and 36 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

42. Use total distance and total time 8

Question. On an invented two-stage journey, stage one covers 50 km in 1.25 h, and stage two covers 90 km in 1.75 h. Find overall average speed.

Work it through. Total distance is 50+90=140 km. Total elapsed time is 1.25+1.75=3 h. Divide totals: 140/3=46.667 km/h (rounded as displayed).

Check. 46.667×3≈140 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

43. Use total distance and total time 9

Question. On an invented two-stage journey, stage one covers 90 km in 1.5 h, and stage two covers 30 km in 0.5 h. Find overall average speed.

Work it through. Total distance is 90+30=120 km. Total elapsed time is 1.5+0.5=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

44. Use total distance and total time 10

Question. On an invented two-stage journey, stage one covers 36 km in 0.75 h, and stage two covers 84 km in 1.75 h. Find overall average speed.

Work it through. Total distance is 36+84=120 km. Total elapsed time is 0.75+1.75=2.5 h. Divide totals: 120/2.5=48 km/h.

Check. 48×2.5≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 48 and 48 km/h. Compare them with the overall 48. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

45. Use total distance and total time 11

Question. On an invented two-stage journey, stage one covers 65 km in 1.3 h, and stage two covers 35 km in 0.7 h. Find overall average speed.

Work it through. Total distance is 65+35=100 km. Total elapsed time is 1.3+0.7=2 h. Divide totals: 100/2=50 km/h.

Check. 50×2≈100 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 50 and 50 km/h. Compare them with the overall 50. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

46. Reason about a rate or elapsed time 1

Question. An office printer makes 144 pages in 12 minutes. What is its average pages per minute?

Work it through. 144 ÷ 12 = 12 pages/min.

First wrong step to avoid. Reading 12 as minutes per page, which reverses the rate.

Check. At this rate 5 minutes produces 60 pages.

47. Reason about a rate or elapsed time 2

Question. A tap adds 48 litres in eight minutes. What is its average flow?

Work it through. 48 ÷ 8 = 6 L/min.

First wrong step to avoid. Writing 6 min/L rather than litres per minute.

Check. Check 6 L/min × 8 min = 48 L.

48. Reason about a rate or elapsed time 3

Question. A machine makes 84 labels in seven minutes. How long for 132 labels at constant rate?

Work it through. Its rate is 84/7=12 labels/min. Required time is 132/12 = 11 minutes.

First wrong step to avoid. Multiplying labels by the rate rather than dividing to find time.

Check. 12 labels/min × 11 min = 132 labels.

49. Reason about a rate or elapsed time 4

Question. A student reads 24 pages in 30 minutes at a constant pace. What is the page rate?

Work it through. Rate=24/30=0.8 pages/min, or 48 pages/hour.

First wrong step to avoid. Reporting 1.25 pages/min, which is the minutes per page instead.

Check. Check 0.8×30=24 pages.

50. Reason about a rate or elapsed time 5

Question. A fictional pump moves 90 L in six minutes. How long for 225 L at the same rate?

Work it through. Rate=90/6=15 L/min. Time=225/15=15 minutes.

First wrong step to avoid. Using 225×15 and obtaining an amount with incorrect units.

Check. 15 L/min × 15 min = 225 L.

51. Reason about a rate or elapsed time 6

Question. Convert 2.5 hours to hours and minutes.

Work it through. 0.5 h is thirty minutes, so 2 h 30 min.

First wrong step to avoid. Reading 2.5 as two hours five minutes.

Check. 2 + 30/60 = 2.5 hours.

52. Reason about a rate or elapsed time 7

Question. Convert one hour 12 minutes to decimal hours.

Work it through. 12/60 = 0.2 hour, so total is 1.2 hours.

First wrong step to avoid. Writing 1.12 hours by treating minutes as decimal hundredths.

Check. 1.2×60=72 minutes.

53. Reason about a rate or elapsed time 8

Question. A car covers 150 km at uniform 50 km/h. Find duration.

Work it through. Time=distance/speed=150/50=3 h.

First wrong step to avoid. Multiplying speed and distance to find time.

Check. 50 km/h × 3 h = 150 km.

54. Reason about a rate or elapsed time 9

Question. A cyclist travels at constant 18 km/h for 40 minutes. Find distance.

Work it through. 40 minutes is 2/3 hour. Distance=18×(2/3)=12 km.

First wrong step to avoid. Using 18×40 as if minutes were hours.

Check. 12 km/(2/3 h)=18 km/h.

55. Reason about a rate or elapsed time 10

Question. A journey covers 30 km at 60 km/h, then includes a 30-minute stop. Find average speed for the full elapsed hour.

Work it through. Moving time is 0.5 h and stopped time is 0.5 h. Total elapsed is one hour, so average speed=30 km/h.

First wrong step to avoid. Ignoring stationary time and reporting 60 km/h for the whole elapsed interval.

Check. 30 km÷1 h=30 km/h; be clear about what the question calls elapsed time.

56. Reason about a rate or elapsed time 11

Question. A walker covers 3 km in 30 minutes and then rests 15 minutes. Find average speed across the entire interval.

Work it through. Distance=3 km; elapsed time=45 min=0.75 h, so speed=3/0.75=4 km/h.

First wrong step to avoid. Using only walking time when the problem includes the rest in the requested interval.

Check. 3 km÷0.75 h=4 km/h.

57. Reason about a rate or elapsed time 12

Question. Outward distance 60 km at 60 km/h, return distance 60 km at 30 km/h. Find full-trip average speed.

Work it through. Outward time=1 h, return time=2 h, total distance=120 km and total time=3 h, so average=40 km/h.

First wrong step to avoid. Averaging 60 and 30 to 45 km/h is wrong because journey times differ.

Check. 40×3=120 km; this is the unequal-time equal-distance trap.

58. Reason about a rate or elapsed time 13

Question. For the same fixed 180-km journey, compare 60 km/h with 90 km/h travel times.

Work it through. At 60 km/h, time=180/60=3 h. At 90 km/h, time=180/90=2 h. Faster travel saves one hour in the ideal constant-speed model.

First wrong step to avoid. Calling the time saving 30 minutes because the speed rose by 30 km/h.

Check. Check both speed×time products equal 180 km.

59. Reason about a rate or elapsed time 14

Question. A hypothetical conveyor carries 360 parts in 15 minutes. Find parts per hour.

Work it through. Rate=360/15=24 parts/min, or 24×60=1440 parts/hour.

First wrong step to avoid. Dividing by 60 when converting a per-minute count into a per-hour count.

Check. 1440/60=24 parts/min.

60. Reason about a rate or elapsed time 15

Question. A tank holds 240 L and fills at a constant 20 L/min. How long to fill from empty?

Work it through. Time=240/20=12 minutes.

First wrong step to avoid. Multiplying 240×20, which has units L²/min.

Check. 20 L/min × 12 min = 240 L.

61. Reason about a rate or elapsed time 16

Question. A vehicle travels at 5 m/s for 12 seconds. Find its distance.

Work it through. Distance=5×12=60 m.

First wrong step to avoid. Giving 60 m/s when the requested quantity is distance.

Check. 60m/12s=5m/s.

62. Reason about a rate or elapsed time 17

Question. A student says 72 km/h equals 72 m/s. Explain the error.

Work it through. The numerical value changes under unit conversion: 72 km/h ÷ 3.6 = 20 m/s.

First wrong step to avoid. Assuming two units of speed use the same number.

Check. 20 m/s is 72 km/h because 20×3.6=72.

63. Reason about a rate or elapsed time 18

Question. A 120-km trip has a 90-minute moving period and a 30-minute stop. What is average speed including stop?

Work it through. Total elapsed=120 min=2 h, so average speed=60 km/h.

First wrong step to avoid. Dividing by 1.5 h instead of the full two hours requested.

Check. 60 km/h×2 h=120 km.

64. Reason about a rate or elapsed time 19

Question. A rate is 36 km/h. How far is travelled in 15 minutes at constant speed?

Work it through. 15 min=0.25 h; distance=36×0.25=9 km.

First wrong step to avoid. Treating fifteen minutes as 0.15 hour.

Check. 9 km/0.25 h=36 km/h.

65. Reason about a rate or elapsed time 20

Question. Two journeys have equal distance but different average speeds. Which one takes longer?

Work it through. At fixed distance, time=distance/speed, so the one with lower average speed takes longer, assuming the same definition of elapsed time.

First wrong step to avoid. Concluding that a larger km/h number means larger hours.

Check. Use 100 km at 50 km/h (2 h) and 100 km at 100 km/h (1 h).

66. Reason about a rate or elapsed time 21

Question. A numerical answer of 3 may represent different units. How can a pupil decide?

Work it through. Read the requested quantity and analyse units: km÷(km/h) gives hours; km÷h gives km/h; km/h×h gives kilometres.

First wrong step to avoid. Writing only 3 without units because the arithmetic looks tidy.

Check. Show the cancellation in each case, then state the correct noun.

Five typical speed mistakes and their repairs

error1

error2

error3

error4

error5

How an illustrative three-pupil tutorial might work

First 10 minutes: retrieve metric and time conversions without a calculator.
Next 20 minutes: derive the speed formulas from units and convert both km/h and m/s.
Next 25 minutes: individual mixed speed and time problems with first-line feedback.
Next 15 minutes: compare stage-speed arithmetic with whole-trip average speed.
Next 10 minutes: unseen mixed rates including print output or liquid flow.
Final 10 minutes: recheck units and plan short retrieval practice.

Five short home sessions

Monday: derive the 3.6 conversion factor from 1000 and 3600, then convert six speeds both ways.
Tuesday: convert minutes and mixed hours into decimal hours and back.
Wednesday: solve two questions each for distance, speed and duration.
Thursday: find total distance and elapsed time for two-stage journeys; include one with a stop.
Friday: practise non-travel rates, then re-solve the week’s first mistaken calculation without viewing the answer.

G1 subject level and the published 2027 SEC syllabus

Frequently asked questions

faq1

Because one kilometre is 1000 metres and one hour is 3600 seconds; 1000/3600=1/3.6.

faq2

faq3

It counts when the question defines total elapsed journey time to include that stop. Read the requested interval carefully.

faq4

The stages may have unequal durations or distances. The whole-trip average comes from total distance and total time; an unweighted mean can be wrong.

faq5

The underlying concept is the same: output divided by time. Preserve the actual units such as pages/min or L/min.

faq6

Yes. It is explicitly listed in the MOE Secondary Two G1 N4 content. School assessment dates and emphasis vary.

Official references and reader note

Average speed = total distance ÷ total elapsed time, for the interval the question defines.
Distance = speed × time, for constant-speed motion or a suitable average over a defined interval.
Time = distance ÷ speed, where speed is nonzero and definitions match.

To convert km/h to m/s, divide by 3.6. To convert m/s to km/h, multiply by 3.6. The factor comes from 1000 metres in one kilometre and 3600 seconds in one hour. A calculation is not complete until the output uses the unit requested by the question.

This guide is for a Secondary 2 G1 Mathematics pupil in Bukit Timah. MOE’s G1 Secondary Two N4 topic includes rates and average rates, speed and average speed, and unit conversions such as km/h to m/s. These numerical skills are not the same as assuming distance-time or speed-time graph interpretation is required in the 2027 K110 SEC syllabus.

Jump to the explanation you need

One-minute speed diagnostic
Why the 3.6 factor works
Average speed across stages and stops
50-plus original speed clinics
First-error diagnosis
Three-pupil tutorial model
A five-day revision plan
FAQs
Official sources

A 60-second diagnostic

Speed conversion is a ratio of units

one

two

three

Average speed depends on both totals

total

rest

direction

Original rate, speed and unit-conversion clinics

1. Convert km/h to m/s 1

Question. An imaginary vehicle has a stated speed of 18 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 18×1000/3600 = 18/3.6 = 5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 5 m/s by 3.6 to recover 18 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

2. Convert km/h to m/s 2

Question. An imaginary vehicle has a stated speed of 27 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 27×1000/3600 = 27/3.6 = 7.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 7.5 m/s by 3.6 to recover 27 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

3. Convert km/h to m/s 3

Question. An imaginary vehicle has a stated speed of 36 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 36×1000/3600 = 36/3.6 = 10 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 10 m/s by 3.6 to recover 36 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

4. Convert km/h to m/s 4

Question. An imaginary vehicle has a stated speed of 45 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 45×1000/3600 = 45/3.6 = 12.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 12.5 m/s by 3.6 to recover 45 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

5. Convert km/h to m/s 5

Question. An imaginary vehicle has a stated speed of 54 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 54×1000/3600 = 54/3.6 = 15 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 15 m/s by 3.6 to recover 54 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

6. Convert km/h to m/s 6

Question. An imaginary vehicle has a stated speed of 63 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 63×1000/3600 = 63/3.6 = 17.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 17.5 m/s by 3.6 to recover 63 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

7. Convert km/h to m/s 7

Question. An imaginary vehicle has a stated speed of 72 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 72×1000/3600 = 72/3.6 = 20 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 20 m/s by 3.6 to recover 72 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

8. Convert km/h to m/s 8

Question. An imaginary vehicle has a stated speed of 81 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 81×1000/3600 = 81/3.6 = 22.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 22.5 m/s by 3.6 to recover 81 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

9. Convert km/h to m/s 9

Question. An imaginary vehicle has a stated speed of 90 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 90×1000/3600 = 90/3.6 = 25 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 25 m/s by 3.6 to recover 90 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

10. Convert km/h to m/s 10

Question. An imaginary vehicle has a stated speed of 108 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 108×1000/3600 = 108/3.6 = 30 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 30 m/s by 3.6 to recover 108 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

11. Convert km/h to m/s 11

Question. An imaginary vehicle has a stated speed of 144 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 144×1000/3600 = 144/3.6 = 40 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 40 m/s by 3.6 to recover 144 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

12. Convert km/h to m/s 12

Question. An imaginary vehicle has a stated speed of 9 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 9×1000/3600 = 9/3.6 = 2.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 2.5 m/s by 3.6 to recover 9 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

13. Convert m/s to km/h 1

Question. A fictional moving object travels at 2.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 2.5×3.6 = 9 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 9 km/h by 3.6 to recover 2.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 2.5 m/s gives 50 metres. Compute the same distance using 9 km/h and time 20/3600 hours; the two methods must agree.

14. Convert m/s to km/h 2

Question. A fictional moving object travels at 5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 5×3.6 = 18 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 18 km/h by 3.6 to recover 5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 5 m/s gives 100 metres. Compute the same distance using 18 km/h and time 20/3600 hours; the two methods must agree.

15. Convert m/s to km/h 3

Question. A fictional moving object travels at 7.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 7.5×3.6 = 27 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 27 km/h by 3.6 to recover 7.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 7.5 m/s gives 150 metres. Compute the same distance using 27 km/h and time 20/3600 hours; the two methods must agree.

16. Convert m/s to km/h 4

Question. A fictional moving object travels at 10 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 10×3.6 = 36 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 36 km/h by 3.6 to recover 10 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 10 m/s gives 200 metres. Compute the same distance using 36 km/h and time 20/3600 hours; the two methods must agree.

17. Convert m/s to km/h 5

Question. A fictional moving object travels at 12.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 12.5×3.6 = 45 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 45 km/h by 3.6 to recover 12.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 12.5 m/s gives 250 metres. Compute the same distance using 45 km/h and time 20/3600 hours; the two methods must agree.

18. Convert m/s to km/h 6

Question. A fictional moving object travels at 15 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 15×3.6 = 54 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 54 km/h by 3.6 to recover 15 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 15 m/s gives 300 metres. Compute the same distance using 54 km/h and time 20/3600 hours; the two methods must agree.

19. Convert m/s to km/h 7

Question. A fictional moving object travels at 17.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 17.5×3.6 = 63 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 63 km/h by 3.6 to recover 17.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 17.5 m/s gives 350 metres. Compute the same distance using 63 km/h and time 20/3600 hours; the two methods must agree.

20. Convert m/s to km/h 8

Question. A fictional moving object travels at 20 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 20×3.6 = 72 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 72 km/h by 3.6 to recover 20 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 20 m/s gives 400 metres. Compute the same distance using 72 km/h and time 20/3600 hours; the two methods must agree.

21. Convert m/s to km/h 9

Question. A fictional moving object travels at 22.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 22.5×3.6 = 81 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 81 km/h by 3.6 to recover 22.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 22.5 m/s gives 450 metres. Compute the same distance using 81 km/h and time 20/3600 hours; the two methods must agree.

22. Convert m/s to km/h 10

Question. A fictional moving object travels at 25 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 25×3.6 = 90 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 90 km/h by 3.6 to recover 25 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 25 m/s gives 500 metres. Compute the same distance using 90 km/h and time 20/3600 hours; the two methods must agree.

23. Find average speed with minutes 1

Question. A hypothetical journey covers 24 km in 30 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 30 min to 0.5 h. Average speed is distance ÷ time = 24 ÷ (30/60) = 48 km/h.

First wrong step to avoid. Dividing 24 by 30 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 0.5 h reproduces 24 km, up to any displayed rounding. The units km/h × h simplify to km.

24. Find average speed with minutes 2

Question. A hypothetical journey covers 45 km in 45 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 45 min to 0.75 h. Average speed is distance ÷ time = 45 ÷ (45/60) = 60 km/h.

First wrong step to avoid. Dividing 45 by 45 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 60 km/h multiplied by 0.75 h reproduces 45 km, up to any displayed rounding. The units km/h × h simplify to km.

25. Find average speed with minutes 3

Question. A hypothetical journey covers 60 km in 75 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 75 min to 1.25 h. Average speed is distance ÷ time = 60 ÷ (75/60) = 48 km/h.

First wrong step to avoid. Dividing 60 by 75 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 1.25 h reproduces 60 km, up to any displayed rounding. The units km/h × h simplify to km.

26. Find average speed with minutes 4

Question. A hypothetical journey covers 27 km in 20 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 20 min to 0.33333 h. Average speed is distance ÷ time = 27 ÷ (20/60) = 81 km/h.

First wrong step to avoid. Dividing 27 by 20 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 81 km/h multiplied by 0.33333 h reproduces 27 km, up to any displayed rounding. The units km/h × h simplify to km.

27. Find average speed with minutes 5

Question. A hypothetical journey covers 36 km in 50 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 50 min to 0.83333 h. Average speed is distance ÷ time = 36 ÷ (50/60) = 43.2 km/h.

First wrong step to avoid. Dividing 36 by 50 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 43.2 km/h multiplied by 0.83333 h reproduces 36 km, up to any displayed rounding. The units km/h × h simplify to km.

28. Find average speed with minutes 6

Question. A hypothetical journey covers 105 km in 90 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 90 min to 1.5 h. Average speed is distance ÷ time = 105 ÷ (90/60) = 70 km/h.

First wrong step to avoid. Dividing 105 by 90 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 70 km/h multiplied by 1.5 h reproduces 105 km, up to any displayed rounding. The units km/h × h simplify to km.

29. Find average speed with minutes 7

Question. A hypothetical journey covers 12 km in 15 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 15 min to 0.25 h. Average speed is distance ÷ time = 12 ÷ (15/60) = 48 km/h.

First wrong step to avoid. Dividing 12 by 15 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 0.25 h reproduces 12 km, up to any displayed rounding. The units km/h × h simplify to km.

30. Find average speed with minutes 8

Question. A hypothetical journey covers 96 km in 80 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 80 min to 1.3333 h. Average speed is distance ÷ time = 96 ÷ (80/60) = 72 km/h.

First wrong step to avoid. Dividing 96 by 80 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 72 km/h multiplied by 1.3333 h reproduces 96 km, up to any displayed rounding. The units km/h × h simplify to km.

31. Find average speed with minutes 9

Question. A hypothetical journey covers 14 km in 35 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 35 min to 0.58333 h. Average speed is distance ÷ time = 14 ÷ (35/60) = 24 km/h.

First wrong step to avoid. Dividing 14 by 35 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 24 km/h multiplied by 0.58333 h reproduces 14 km, up to any displayed rounding. The units km/h × h simplify to km.

32. Find average speed with minutes 10

Question. A hypothetical journey covers 33 km in 22 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 22 min to 0.36667 h. Average speed is distance ÷ time = 33 ÷ (22/60) = 90 km/h.

First wrong step to avoid. Dividing 33 by 22 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 90 km/h multiplied by 0.36667 h reproduces 33 km, up to any displayed rounding. The units km/h × h simplify to km.

33. Find average speed with minutes 11

Question. A hypothetical journey covers 75 km in 50 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 50 min to 0.83333 h. Average speed is distance ÷ time = 75 ÷ (50/60) = 90 km/h.

First wrong step to avoid. Dividing 75 by 50 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 90 km/h multiplied by 0.83333 h reproduces 75 km, up to any displayed rounding. The units km/h × h simplify to km.

34. Find average speed with minutes 12

Question. A hypothetical journey covers 126 km in 105 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 105 min to 1.75 h. Average speed is distance ÷ time = 126 ÷ (105/60) = 72 km/h.

First wrong step to avoid. Dividing 126 by 105 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 72 km/h multiplied by 1.75 h reproduces 126 km, up to any displayed rounding. The units km/h × h simplify to km.

35. Use total distance and total time 1

Question. On an invented two-stage journey, stage one covers 60 km in 1 h, and stage two covers 60 km in 2 h. Find overall average speed.

Work it through. Total distance is 60+60=120 km. Total elapsed time is 1+2=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 30 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

36. Use total distance and total time 2

Question. On an invented two-stage journey, stage one covers 30 km in 0.5 h, and stage two covers 90 km in 1.5 h. Find overall average speed.

Work it through. Total distance is 30+90=120 km. Total elapsed time is 0.5+1.5=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

37. Use total distance and total time 3

Question. On an invented two-stage journey, stage one covers 80 km in 2 h, and stage two covers 40 km in 0.5 h. Find overall average speed.

Work it through. Total distance is 80+40=120 km. Total elapsed time is 2+0.5=2.5 h. Divide totals: 120/2.5=48 km/h.

Check. 48×2.5≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 40 and 80 km/h. Compare them with the overall 48. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

38. Use total distance and total time 4

Question. On an invented two-stage journey, stage one covers 70 km in 1 h, and stage two covers 30 km in 1.5 h. Find overall average speed.

Work it through. Total distance is 70+30=100 km. Total elapsed time is 1+1.5=2.5 h. Divide totals: 100/2.5=40 km/h.

Check. 40×2.5≈100 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 70 and 20 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

39. Use total distance and total time 5

Question. On an invented two-stage journey, stage one covers 45 km in 0.75 h, and stage two covers 75 km in 1.25 h. Find overall average speed.

Work it through. Total distance is 45+75=120 km. Total elapsed time is 0.75+1.25=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

40. Use total distance and total time 6

Question. On an invented two-stage journey, stage one covers 20 km in 0.5 h, and stage two covers 100 km in 2.5 h. Find overall average speed.

Work it through. Total distance is 20+100=120 km. Total elapsed time is 0.5+2.5=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 40 and 40 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

41. Use total distance and total time 7

Question. On an invented two-stage journey, stage one covers 48 km in 1 h, and stage two covers 72 km in 2 h. Find overall average speed.

Work it through. Total distance is 48+72=120 km. Total elapsed time is 1+2=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 48 and 36 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

42. Use total distance and total time 8

Question. On an invented two-stage journey, stage one covers 50 km in 1.25 h, and stage two covers 90 km in 1.75 h. Find overall average speed.

Work it through. Total distance is 50+90=140 km. Total elapsed time is 1.25+1.75=3 h. Divide totals: 140/3=46.667 km/h (rounded as displayed).

Check. 46.667×3≈140 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

43. Use total distance and total time 9

Question. On an invented two-stage journey, stage one covers 90 km in 1.5 h, and stage two covers 30 km in 0.5 h. Find overall average speed.

Work it through. Total distance is 90+30=120 km. Total elapsed time is 1.5+0.5=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

44. Use total distance and total time 10

Question. On an invented two-stage journey, stage one covers 36 km in 0.75 h, and stage two covers 84 km in 1.75 h. Find overall average speed.

Work it through. Total distance is 36+84=120 km. Total elapsed time is 0.75+1.75=2.5 h. Divide totals: 120/2.5=48 km/h.

Check. 48×2.5≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 48 and 48 km/h. Compare them with the overall 48. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

45. Use total distance and total time 11

Question. On an invented two-stage journey, stage one covers 65 km in 1.3 h, and stage two covers 35 km in 0.7 h. Find overall average speed.

Work it through. Total distance is 65+35=100 km. Total elapsed time is 1.3+0.7=2 h. Divide totals: 100/2=50 km/h.

Check. 50×2≈100 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 50 and 50 km/h. Compare them with the overall 50. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

46. Reason about a rate or elapsed time 1

Question. An office printer makes 144 pages in 12 minutes. What is its average pages per minute?

Work it through. 144 ÷ 12 = 12 pages/min.

First wrong step to avoid. Reading 12 as minutes per page, which reverses the rate.

Check. At this rate 5 minutes produces 60 pages.

47. Reason about a rate or elapsed time 2

Question. A tap adds 48 litres in eight minutes. What is its average flow?

Work it through. 48 ÷ 8 = 6 L/min.

First wrong step to avoid. Writing 6 min/L rather than litres per minute.

Check. Check 6 L/min × 8 min = 48 L.

48. Reason about a rate or elapsed time 3

Question. A machine makes 84 labels in seven minutes. How long for 132 labels at constant rate?

Work it through. Its rate is 84/7=12 labels/min. Required time is 132/12 = 11 minutes.

First wrong step to avoid. Multiplying labels by the rate rather than dividing to find time.

Check. 12 labels/min × 11 min = 132 labels.

49. Reason about a rate or elapsed time 4

Question. A student reads 24 pages in 30 minutes at a constant pace. What is the page rate?

Work it through. Rate=24/30=0.8 pages/min, or 48 pages/hour.

First wrong step to avoid. Reporting 1.25 pages/min, which is the minutes per page instead.

Check. Check 0.8×30=24 pages.

50. Reason about a rate or elapsed time 5

Question. A fictional pump moves 90 L in six minutes. How long for 225 L at the same rate?

Work it through. Rate=90/6=15 L/min. Time=225/15=15 minutes.

First wrong step to avoid. Using 225×15 and obtaining an amount with incorrect units.

Check. 15 L/min × 15 min = 225 L.

51. Reason about a rate or elapsed time 6

Question. Convert 2.5 hours to hours and minutes.

Work it through. 0.5 h is thirty minutes, so 2 h 30 min.

First wrong step to avoid. Reading 2.5 as two hours five minutes.

Check. 2 + 30/60 = 2.5 hours.

52. Reason about a rate or elapsed time 7

Question. Convert one hour 12 minutes to decimal hours.

Work it through. 12/60 = 0.2 hour, so total is 1.2 hours.

First wrong step to avoid. Writing 1.12 hours by treating minutes as decimal hundredths.

Check. 1.2×60=72 minutes.

53. Reason about a rate or elapsed time 8

Question. A car covers 150 km at uniform 50 km/h. Find duration.

Work it through. Time=distance/speed=150/50=3 h.

First wrong step to avoid. Multiplying speed and distance to find time.

Check. 50 km/h × 3 h = 150 km.

54. Reason about a rate or elapsed time 9

Question. A cyclist travels at constant 18 km/h for 40 minutes. Find distance.

Work it through. 40 minutes is 2/3 hour. Distance=18×(2/3)=12 km.

First wrong step to avoid. Using 18×40 as if minutes were hours.

Check. 12 km/(2/3 h)=18 km/h.

55. Reason about a rate or elapsed time 10

Question. A journey covers 30 km at 60 km/h, then includes a 30-minute stop. Find average speed for the full elapsed hour.

Work it through. Moving time is 0.5 h and stopped time is 0.5 h. Total elapsed is one hour, so average speed=30 km/h.

First wrong step to avoid. Ignoring stationary time and reporting 60 km/h for the whole elapsed interval.

Check. 30 km÷1 h=30 km/h; be clear about what the question calls elapsed time.

56. Reason about a rate or elapsed time 11

Question. A walker covers 3 km in 30 minutes and then rests 15 minutes. Find average speed across the entire interval.

Work it through. Distance=3 km; elapsed time=45 min=0.75 h, so speed=3/0.75=4 km/h.

First wrong step to avoid. Using only walking time when the problem includes the rest in the requested interval.

Check. 3 km÷0.75 h=4 km/h.

57. Reason about a rate or elapsed time 12

Question. Outward distance 60 km at 60 km/h, return distance 60 km at 30 km/h. Find full-trip average speed.

Work it through. Outward time=1 h, return time=2 h, total distance=120 km and total time=3 h, so average=40 km/h.

First wrong step to avoid. Averaging 60 and 30 to 45 km/h is wrong because journey times differ.

Check. 40×3=120 km; this is the unequal-time equal-distance trap.

58. Reason about a rate or elapsed time 13

Question. For the same fixed 180-km journey, compare 60 km/h with 90 km/h travel times.

Work it through. At 60 km/h, time=180/60=3 h. At 90 km/h, time=180/90=2 h. Faster travel saves one hour in the ideal constant-speed model.

First wrong step to avoid. Calling the time saving 30 minutes because the speed rose by 30 km/h.

Check. Check both speed×time products equal 180 km.

59. Reason about a rate or elapsed time 14

Question. A hypothetical conveyor carries 360 parts in 15 minutes. Find parts per hour.

Work it through. Rate=360/15=24 parts/min, or 24×60=1440 parts/hour.

First wrong step to avoid. Dividing by 60 when converting a per-minute count into a per-hour count.

Check. 1440/60=24 parts/min.

60. Reason about a rate or elapsed time 15

Question. A tank holds 240 L and fills at a constant 20 L/min. How long to fill from empty?

Work it through. Time=240/20=12 minutes.

First wrong step to avoid. Multiplying 240×20, which has units L²/min.

Check. 20 L/min × 12 min = 240 L.

61. Reason about a rate or elapsed time 16

Question. A vehicle travels at 5 m/s for 12 seconds. Find its distance.

Work it through. Distance=5×12=60 m.

First wrong step to avoid. Giving 60 m/s when the requested quantity is distance.

Check. 60m/12s=5m/s.

62. Reason about a rate or elapsed time 17

Question. A student says 72 km/h equals 72 m/s. Explain the error.

Work it through. The numerical value changes under unit conversion: 72 km/h ÷ 3.6 = 20 m/s.

First wrong step to avoid. Assuming two units of speed use the same number.

Check. 20 m/s is 72 km/h because 20×3.6=72.

63. Reason about a rate or elapsed time 18

Question. A 120-km trip has a 90-minute moving period and a 30-minute stop. What is average speed including stop?

Work it through. Total elapsed=120 min=2 h, so average speed=60 km/h.

First wrong step to avoid. Dividing by 1.5 h instead of the full two hours requested.

Check. 60 km/h×2 h=120 km.

64. Reason about a rate or elapsed time 19

Question. A rate is 36 km/h. How far is travelled in 15 minutes at constant speed?

Work it through. 15 min=0.25 h; distance=36×0.25=9 km.

First wrong step to avoid. Treating fifteen minutes as 0.15 hour.

Check. 9 km/0.25 h=36 km/h.

65. Reason about a rate or elapsed time 20

Question. Two journeys have equal distance but different average speeds. Which one takes longer?

Work it through. At fixed distance, time=distance/speed, so the one with lower average speed takes longer, assuming the same definition of elapsed time.

First wrong step to avoid. Concluding that a larger km/h number means larger hours.

Check. Use 100 km at 50 km/h (2 h) and 100 km at 100 km/h (1 h).

66. Reason about a rate or elapsed time 21

Question. A numerical answer of 3 may represent different units. How can a pupil decide?

Work it through. Read the requested quantity and analyse units: km÷(km/h) gives hours; km÷h gives km/h; km/h×h gives kilometres.

First wrong step to avoid. Writing only 3 without units because the arithmetic looks tidy.

Check. Show the cancellation in each case, then state the correct noun.

Five typical speed mistakes and their repairs

error1

error2

error3

error4

error5

How an illustrative three-pupil tutorial might work

First 10 minutes: retrieve metric and time conversions without a calculator.
Next 20 minutes: derive the speed formulas from units and convert both km/h and m/s.
Next 25 minutes: individual mixed speed and time problems with first-line feedback.
Next 15 minutes: compare stage-speed arithmetic with whole-trip average speed.
Next 10 minutes: unseen mixed rates including print output or liquid flow.
Final 10 minutes: recheck units and plan short retrieval practice.

Five short home sessions

Monday: derive the 3.6 conversion factor from 1000 and 3600, then convert six speeds both ways.
Tuesday: convert minutes and mixed hours into decimal hours and back.
Wednesday: solve two questions each for distance, speed and duration.
Thursday: find total distance and elapsed time for two-stage journeys; include one with a stop.
Friday: practise non-travel rates, then re-solve the week’s first mistaken calculation without viewing the answer.

G1 subject level and the published 2027 SEC syllabus

Frequently asked questions

faq1

Because one kilometre is 1000 metres and one hour is 3600 seconds; 1000/3600=1/3.6.

faq2

faq3

It counts when the question defines total elapsed journey time to include that stop. Read the requested interval carefully.

faq4

The stages may have unequal durations or distances. The whole-trip average comes from total distance and total time; an unweighted mean can be wrong.

faq5

The underlying concept is the same: output divided by time. Preserve the actual units such as pages/min or L/min.

faq6

Yes. It is explicitly listed in the MOE Secondary Two G1 N4 content. School assessment dates and emphasis vary.

Official references and reader note

Average speed = total distance ÷ total elapsed time, for the interval the question defines.
Distance = speed × time, for constant-speed motion or a suitable average over a defined interval.
Time = distance ÷ speed, where speed is nonzero and definitions match.

Jump to the explanation you need

One-minute speed diagnostic
Why the 3.6 factor works
Average speed across stages and stops
50-plus original speed clinics
First-error diagnosis
Three-pupil tutorial model
A five-day revision plan
FAQs
Official sources

A 60-second diagnostic

Speed conversion is a ratio of units

one

two

three

Average speed depends on both totals

total

rest

direction

Original rate, speed and unit-conversion clinics

1. Convert km/h to m/s 1

Question. An imaginary vehicle has a stated speed of 18 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 18×1000/3600 = 18/3.6 = 5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 5 m/s by 3.6 to recover 18 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

2. Convert km/h to m/s 2

Question. An imaginary vehicle has a stated speed of 27 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 27×1000/3600 = 27/3.6 = 7.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 7.5 m/s by 3.6 to recover 27 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

3. Convert km/h to m/s 3

Question. An imaginary vehicle has a stated speed of 36 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 36×1000/3600 = 36/3.6 = 10 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 10 m/s by 3.6 to recover 36 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

4. Convert km/h to m/s 4

Question. An imaginary vehicle has a stated speed of 45 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 45×1000/3600 = 45/3.6 = 12.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 12.5 m/s by 3.6 to recover 45 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

5. Convert km/h to m/s 5

Question. An imaginary vehicle has a stated speed of 54 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 54×1000/3600 = 54/3.6 = 15 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 15 m/s by 3.6 to recover 54 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

6. Convert km/h to m/s 6

Question. An imaginary vehicle has a stated speed of 63 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 63×1000/3600 = 63/3.6 = 17.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 17.5 m/s by 3.6 to recover 63 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

7. Convert km/h to m/s 7

Question. An imaginary vehicle has a stated speed of 72 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 72×1000/3600 = 72/3.6 = 20 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 20 m/s by 3.6 to recover 72 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

8. Convert km/h to m/s 8

Question. An imaginary vehicle has a stated speed of 81 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 81×1000/3600 = 81/3.6 = 22.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 22.5 m/s by 3.6 to recover 81 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

9. Convert km/h to m/s 9

Question. An imaginary vehicle has a stated speed of 90 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 90×1000/3600 = 90/3.6 = 25 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 25 m/s by 3.6 to recover 90 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

10. Convert km/h to m/s 10

Question. An imaginary vehicle has a stated speed of 108 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 108×1000/3600 = 108/3.6 = 30 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 30 m/s by 3.6 to recover 108 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

11. Convert km/h to m/s 11

Question. An imaginary vehicle has a stated speed of 144 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 144×1000/3600 = 144/3.6 = 40 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 40 m/s by 3.6 to recover 144 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

12. Convert km/h to m/s 12

Question. An imaginary vehicle has a stated speed of 9 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 9×1000/3600 = 9/3.6 = 2.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 2.5 m/s by 3.6 to recover 9 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

13. Convert m/s to km/h 1

Question. A fictional moving object travels at 2.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 2.5×3.6 = 9 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 9 km/h by 3.6 to recover 2.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 2.5 m/s gives 50 metres. Compute the same distance using 9 km/h and time 20/3600 hours; the two methods must agree.

14. Convert m/s to km/h 2

Question. A fictional moving object travels at 5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 5×3.6 = 18 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 18 km/h by 3.6 to recover 5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 5 m/s gives 100 metres. Compute the same distance using 18 km/h and time 20/3600 hours; the two methods must agree.

15. Convert m/s to km/h 3

Question. A fictional moving object travels at 7.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 7.5×3.6 = 27 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 27 km/h by 3.6 to recover 7.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 7.5 m/s gives 150 metres. Compute the same distance using 27 km/h and time 20/3600 hours; the two methods must agree.

16. Convert m/s to km/h 4

Question. A fictional moving object travels at 10 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 10×3.6 = 36 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 36 km/h by 3.6 to recover 10 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 10 m/s gives 200 metres. Compute the same distance using 36 km/h and time 20/3600 hours; the two methods must agree.

17. Convert m/s to km/h 5

Question. A fictional moving object travels at 12.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 12.5×3.6 = 45 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 45 km/h by 3.6 to recover 12.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 12.5 m/s gives 250 metres. Compute the same distance using 45 km/h and time 20/3600 hours; the two methods must agree.

18. Convert m/s to km/h 6

Question. A fictional moving object travels at 15 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 15×3.6 = 54 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 54 km/h by 3.6 to recover 15 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 15 m/s gives 300 metres. Compute the same distance using 54 km/h and time 20/3600 hours; the two methods must agree.

19. Convert m/s to km/h 7

Question. A fictional moving object travels at 17.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 17.5×3.6 = 63 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 63 km/h by 3.6 to recover 17.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 17.5 m/s gives 350 metres. Compute the same distance using 63 km/h and time 20/3600 hours; the two methods must agree.

20. Convert m/s to km/h 8

Question. A fictional moving object travels at 20 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 20×3.6 = 72 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 72 km/h by 3.6 to recover 20 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 20 m/s gives 400 metres. Compute the same distance using 72 km/h and time 20/3600 hours; the two methods must agree.

21. Convert m/s to km/h 9

Question. A fictional moving object travels at 22.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 22.5×3.6 = 81 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 81 km/h by 3.6 to recover 22.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 22.5 m/s gives 450 metres. Compute the same distance using 81 km/h and time 20/3600 hours; the two methods must agree.

22. Convert m/s to km/h 10

Question. A fictional moving object travels at 25 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 25×3.6 = 90 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 90 km/h by 3.6 to recover 25 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 25 m/s gives 500 metres. Compute the same distance using 90 km/h and time 20/3600 hours; the two methods must agree.

23. Find average speed with minutes 1

Question. A hypothetical journey covers 24 km in 30 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 30 min to 0.5 h. Average speed is distance ÷ time = 24 ÷ (30/60) = 48 km/h.

First wrong step to avoid. Dividing 24 by 30 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 0.5 h reproduces 24 km, up to any displayed rounding. The units km/h × h simplify to km.

24. Find average speed with minutes 2

Question. A hypothetical journey covers 45 km in 45 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 45 min to 0.75 h. Average speed is distance ÷ time = 45 ÷ (45/60) = 60 km/h.

First wrong step to avoid. Dividing 45 by 45 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 60 km/h multiplied by 0.75 h reproduces 45 km, up to any displayed rounding. The units km/h × h simplify to km.

25. Find average speed with minutes 3

Question. A hypothetical journey covers 60 km in 75 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 75 min to 1.25 h. Average speed is distance ÷ time = 60 ÷ (75/60) = 48 km/h.

First wrong step to avoid. Dividing 60 by 75 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 1.25 h reproduces 60 km, up to any displayed rounding. The units km/h × h simplify to km.

26. Find average speed with minutes 4

Question. A hypothetical journey covers 27 km in 20 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 20 min to 0.33333 h. Average speed is distance ÷ time = 27 ÷ (20/60) = 81 km/h.

First wrong step to avoid. Dividing 27 by 20 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 81 km/h multiplied by 0.33333 h reproduces 27 km, up to any displayed rounding. The units km/h × h simplify to km.

27. Find average speed with minutes 5

Question. A hypothetical journey covers 36 km in 50 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 50 min to 0.83333 h. Average speed is distance ÷ time = 36 ÷ (50/60) = 43.2 km/h.

First wrong step to avoid. Dividing 36 by 50 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 43.2 km/h multiplied by 0.83333 h reproduces 36 km, up to any displayed rounding. The units km/h × h simplify to km.

28. Find average speed with minutes 6

Question. A hypothetical journey covers 105 km in 90 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 90 min to 1.5 h. Average speed is distance ÷ time = 105 ÷ (90/60) = 70 km/h.

First wrong step to avoid. Dividing 105 by 90 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 70 km/h multiplied by 1.5 h reproduces 105 km, up to any displayed rounding. The units km/h × h simplify to km.

29. Find average speed with minutes 7

Question. A hypothetical journey covers 12 km in 15 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 15 min to 0.25 h. Average speed is distance ÷ time = 12 ÷ (15/60) = 48 km/h.

First wrong step to avoid. Dividing 12 by 15 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 0.25 h reproduces 12 km, up to any displayed rounding. The units km/h × h simplify to km.

30. Find average speed with minutes 8

Question. A hypothetical journey covers 96 km in 80 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 80 min to 1.3333 h. Average speed is distance ÷ time = 96 ÷ (80/60) = 72 km/h.

First wrong step to avoid. Dividing 96 by 80 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 72 km/h multiplied by 1.3333 h reproduces 96 km, up to any displayed rounding. The units km/h × h simplify to km.

31. Find average speed with minutes 9

Question. A hypothetical journey covers 14 km in 35 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 35 min to 0.58333 h. Average speed is distance ÷ time = 14 ÷ (35/60) = 24 km/h.

First wrong step to avoid. Dividing 14 by 35 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 24 km/h multiplied by 0.58333 h reproduces 14 km, up to any displayed rounding. The units km/h × h simplify to km.

32. Find average speed with minutes 10

Question. A hypothetical journey covers 33 km in 22 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 22 min to 0.36667 h. Average speed is distance ÷ time = 33 ÷ (22/60) = 90 km/h.

First wrong step to avoid. Dividing 33 by 22 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 90 km/h multiplied by 0.36667 h reproduces 33 km, up to any displayed rounding. The units km/h × h simplify to km.

33. Find average speed with minutes 11

Question. A hypothetical journey covers 75 km in 50 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 50 min to 0.83333 h. Average speed is distance ÷ time = 75 ÷ (50/60) = 90 km/h.

First wrong step to avoid. Dividing 75 by 50 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 90 km/h multiplied by 0.83333 h reproduces 75 km, up to any displayed rounding. The units km/h × h simplify to km.

34. Find average speed with minutes 12

Question. A hypothetical journey covers 126 km in 105 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 105 min to 1.75 h. Average speed is distance ÷ time = 126 ÷ (105/60) = 72 km/h.

First wrong step to avoid. Dividing 126 by 105 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 72 km/h multiplied by 1.75 h reproduces 126 km, up to any displayed rounding. The units km/h × h simplify to km.

35. Use total distance and total time 1

Question. On an invented two-stage journey, stage one covers 60 km in 1 h, and stage two covers 60 km in 2 h. Find overall average speed.

Work it through. Total distance is 60+60=120 km. Total elapsed time is 1+2=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 30 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

36. Use total distance and total time 2

Question. On an invented two-stage journey, stage one covers 30 km in 0.5 h, and stage two covers 90 km in 1.5 h. Find overall average speed.

Work it through. Total distance is 30+90=120 km. Total elapsed time is 0.5+1.5=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

37. Use total distance and total time 3

Question. On an invented two-stage journey, stage one covers 80 km in 2 h, and stage two covers 40 km in 0.5 h. Find overall average speed.

Work it through. Total distance is 80+40=120 km. Total elapsed time is 2+0.5=2.5 h. Divide totals: 120/2.5=48 km/h.

Check. 48×2.5≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 40 and 80 km/h. Compare them with the overall 48. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

38. Use total distance and total time 4

Question. On an invented two-stage journey, stage one covers 70 km in 1 h, and stage two covers 30 km in 1.5 h. Find overall average speed.

Work it through. Total distance is 70+30=100 km. Total elapsed time is 1+1.5=2.5 h. Divide totals: 100/2.5=40 km/h.

Check. 40×2.5≈100 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 70 and 20 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

39. Use total distance and total time 5

Question. On an invented two-stage journey, stage one covers 45 km in 0.75 h, and stage two covers 75 km in 1.25 h. Find overall average speed.

Work it through. Total distance is 45+75=120 km. Total elapsed time is 0.75+1.25=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

40. Use total distance and total time 6

Question. On an invented two-stage journey, stage one covers 20 km in 0.5 h, and stage two covers 100 km in 2.5 h. Find overall average speed.

Work it through. Total distance is 20+100=120 km. Total elapsed time is 0.5+2.5=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 40 and 40 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

41. Use total distance and total time 7

Question. On an invented two-stage journey, stage one covers 48 km in 1 h, and stage two covers 72 km in 2 h. Find overall average speed.

Work it through. Total distance is 48+72=120 km. Total elapsed time is 1+2=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 48 and 36 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

42. Use total distance and total time 8

Question. On an invented two-stage journey, stage one covers 50 km in 1.25 h, and stage two covers 90 km in 1.75 h. Find overall average speed.

Work it through. Total distance is 50+90=140 km. Total elapsed time is 1.25+1.75=3 h. Divide totals: 140/3=46.667 km/h (rounded as displayed).

Check. 46.667×3≈140 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

43. Use total distance and total time 9

Question. On an invented two-stage journey, stage one covers 90 km in 1.5 h, and stage two covers 30 km in 0.5 h. Find overall average speed.

Work it through. Total distance is 90+30=120 km. Total elapsed time is 1.5+0.5=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

44. Use total distance and total time 10

Question. On an invented two-stage journey, stage one covers 36 km in 0.75 h, and stage two covers 84 km in 1.75 h. Find overall average speed.

Work it through. Total distance is 36+84=120 km. Total elapsed time is 0.75+1.75=2.5 h. Divide totals: 120/2.5=48 km/h.

Check. 48×2.5≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 48 and 48 km/h. Compare them with the overall 48. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

45. Use total distance and total time 11

Question. On an invented two-stage journey, stage one covers 65 km in 1.3 h, and stage two covers 35 km in 0.7 h. Find overall average speed.

Work it through. Total distance is 65+35=100 km. Total elapsed time is 1.3+0.7=2 h. Divide totals: 100/2=50 km/h.

Check. 50×2≈100 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 50 and 50 km/h. Compare them with the overall 50. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

46. Reason about a rate or elapsed time 1

Question. An office printer makes 144 pages in 12 minutes. What is its average pages per minute?

Work it through. 144 ÷ 12 = 12 pages/min.

First wrong step to avoid. Reading 12 as minutes per page, which reverses the rate.

Check. At this rate 5 minutes produces 60 pages.

47. Reason about a rate or elapsed time 2

Question. A tap adds 48 litres in eight minutes. What is its average flow?

Work it through. 48 ÷ 8 = 6 L/min.

First wrong step to avoid. Writing 6 min/L rather than litres per minute.

Check. Check 6 L/min × 8 min = 48 L.

48. Reason about a rate or elapsed time 3

Question. A machine makes 84 labels in seven minutes. How long for 132 labels at constant rate?

Work it through. Its rate is 84/7=12 labels/min. Required time is 132/12 = 11 minutes.

First wrong step to avoid. Multiplying labels by the rate rather than dividing to find time.

Check. 12 labels/min × 11 min = 132 labels.

49. Reason about a rate or elapsed time 4

Question. A student reads 24 pages in 30 minutes at a constant pace. What is the page rate?

Work it through. Rate=24/30=0.8 pages/min, or 48 pages/hour.

First wrong step to avoid. Reporting 1.25 pages/min, which is the minutes per page instead.

Check. Check 0.8×30=24 pages.

50. Reason about a rate or elapsed time 5

Question. A fictional pump moves 90 L in six minutes. How long for 225 L at the same rate?

Work it through. Rate=90/6=15 L/min. Time=225/15=15 minutes.

First wrong step to avoid. Using 225×15 and obtaining an amount with incorrect units.

Check. 15 L/min × 15 min = 225 L.

51. Reason about a rate or elapsed time 6

Question. Convert 2.5 hours to hours and minutes.

Work it through. 0.5 h is thirty minutes, so 2 h 30 min.

First wrong step to avoid. Reading 2.5 as two hours five minutes.

Check. 2 + 30/60 = 2.5 hours.

52. Reason about a rate or elapsed time 7

Question. Convert one hour 12 minutes to decimal hours.

Work it through. 12/60 = 0.2 hour, so total is 1.2 hours.

First wrong step to avoid. Writing 1.12 hours by treating minutes as decimal hundredths.

Check. 1.2×60=72 minutes.

53. Reason about a rate or elapsed time 8

Question. A car covers 150 km at uniform 50 km/h. Find duration.

Work it through. Time=distance/speed=150/50=3 h.

First wrong step to avoid. Multiplying speed and distance to find time.

Check. 50 km/h × 3 h = 150 km.

54. Reason about a rate or elapsed time 9

Question. A cyclist travels at constant 18 km/h for 40 minutes. Find distance.

Work it through. 40 minutes is 2/3 hour. Distance=18×(2/3)=12 km.

First wrong step to avoid. Using 18×40 as if minutes were hours.

Check. 12 km/(2/3 h)=18 km/h.

55. Reason about a rate or elapsed time 10

Question. A journey covers 30 km at 60 km/h, then includes a 30-minute stop. Find average speed for the full elapsed hour.

Work it through. Moving time is 0.5 h and stopped time is 0.5 h. Total elapsed is one hour, so average speed=30 km/h.

First wrong step to avoid. Ignoring stationary time and reporting 60 km/h for the whole elapsed interval.

Check. 30 km÷1 h=30 km/h; be clear about what the question calls elapsed time.

56. Reason about a rate or elapsed time 11

Question. A walker covers 3 km in 30 minutes and then rests 15 minutes. Find average speed across the entire interval.

Work it through. Distance=3 km; elapsed time=45 min=0.75 h, so speed=3/0.75=4 km/h.

First wrong step to avoid. Using only walking time when the problem includes the rest in the requested interval.

Check. 3 km÷0.75 h=4 km/h.

57. Reason about a rate or elapsed time 12

Question. Outward distance 60 km at 60 km/h, return distance 60 km at 30 km/h. Find full-trip average speed.

Work it through. Outward time=1 h, return time=2 h, total distance=120 km and total time=3 h, so average=40 km/h.

First wrong step to avoid. Averaging 60 and 30 to 45 km/h is wrong because journey times differ.

Check. 40×3=120 km; this is the unequal-time equal-distance trap.

58. Reason about a rate or elapsed time 13

Question. For the same fixed 180-km journey, compare 60 km/h with 90 km/h travel times.

Work it through. At 60 km/h, time=180/60=3 h. At 90 km/h, time=180/90=2 h. Faster travel saves one hour in the ideal constant-speed model.

First wrong step to avoid. Calling the time saving 30 minutes because the speed rose by 30 km/h.

Check. Check both speed×time products equal 180 km.

59. Reason about a rate or elapsed time 14

Question. A hypothetical conveyor carries 360 parts in 15 minutes. Find parts per hour.

Work it through. Rate=360/15=24 parts/min, or 24×60=1440 parts/hour.

First wrong step to avoid. Dividing by 60 when converting a per-minute count into a per-hour count.

Check. 1440/60=24 parts/min.

60. Reason about a rate or elapsed time 15

Question. A tank holds 240 L and fills at a constant 20 L/min. How long to fill from empty?

Work it through. Time=240/20=12 minutes.

First wrong step to avoid. Multiplying 240×20, which has units L²/min.

Check. 20 L/min × 12 min = 240 L.

61. Reason about a rate or elapsed time 16

Question. A vehicle travels at 5 m/s for 12 seconds. Find its distance.

Work it through. Distance=5×12=60 m.

First wrong step to avoid. Giving 60 m/s when the requested quantity is distance.

Check. 60m/12s=5m/s.

62. Reason about a rate or elapsed time 17

Question. A student says 72 km/h equals 72 m/s. Explain the error.

Work it through. The numerical value changes under unit conversion: 72 km/h ÷ 3.6 = 20 m/s.

First wrong step to avoid. Assuming two units of speed use the same number.

Check. 20 m/s is 72 km/h because 20×3.6=72.

63. Reason about a rate or elapsed time 18

Question. A 120-km trip has a 90-minute moving period and a 30-minute stop. What is average speed including stop?

Work it through. Total elapsed=120 min=2 h, so average speed=60 km/h.

First wrong step to avoid. Dividing by 1.5 h instead of the full two hours requested.

Check. 60 km/h×2 h=120 km.

64. Reason about a rate or elapsed time 19

Question. A rate is 36 km/h. How far is travelled in 15 minutes at constant speed?

Work it through. 15 min=0.25 h; distance=36×0.25=9 km.

First wrong step to avoid. Treating fifteen minutes as 0.15 hour.

Check. 9 km/0.25 h=36 km/h.

65. Reason about a rate or elapsed time 20

Question. Two journeys have equal distance but different average speeds. Which one takes longer?

Work it through. At fixed distance, time=distance/speed, so the one with lower average speed takes longer, assuming the same definition of elapsed time.

First wrong step to avoid. Concluding that a larger km/h number means larger hours.

Check. Use 100 km at 50 km/h (2 h) and 100 km at 100 km/h (1 h).

66. Reason about a rate or elapsed time 21

Question. A numerical answer of 3 may represent different units. How can a pupil decide?

Work it through. Read the requested quantity and analyse units: km÷(km/h) gives hours; km÷h gives km/h; km/h×h gives kilometres.

First wrong step to avoid. Writing only 3 without units because the arithmetic looks tidy.

Check. Show the cancellation in each case, then state the correct noun.

Five typical speed mistakes and their repairs

error1

error2

error3

error4

error5

How an illustrative three-pupil tutorial might work

First 10 minutes: retrieve metric and time conversions without a calculator.
Next 20 minutes: derive the speed formulas from units and convert both km/h and m/s.
Next 25 minutes: individual mixed speed and time problems with first-line feedback.
Next 15 minutes: compare stage-speed arithmetic with whole-trip average speed.
Next 10 minutes: unseen mixed rates including print output or liquid flow.
Final 10 minutes: recheck units and plan short retrieval practice.

Five short home sessions

Monday: derive the 3.6 conversion factor from 1000 and 3600, then convert six speeds both ways.
Tuesday: convert minutes and mixed hours into decimal hours and back.
Wednesday: solve two questions each for distance, speed and duration.
Thursday: find total distance and elapsed time for two-stage journeys; include one with a stop.
Friday: practise non-travel rates, then re-solve the week’s first mistaken calculation without viewing the answer.

G1 subject level and the published 2027 SEC syllabus

Frequently asked questions

faq1

Because one kilometre is 1000 metres and one hour is 3600 seconds; 1000/3600=1/3.6.

faq2

faq3

It counts when the question defines total elapsed journey time to include that stop. Read the requested interval carefully.

faq4

The stages may have unequal durations or distances. The whole-trip average comes from total distance and total time; an unweighted mean can be wrong.

faq5

The underlying concept is the same: output divided by time. Preserve the actual units such as pages/min or L/min.

faq6

Yes. It is explicitly listed in the MOE Secondary Two G1 N4 content. School assessment dates and emphasis vary.

Official references and reader note

Did you know? A vehicle may travel at 60 km/h during one part of a journey but have a much lower average speed across the entire trip, especially when slower segments or stops are included. The trick in Secondary 2 G1 Mathematics is not another complicated speed formula. It is knowing which distance and which period of time belong together, and keeping units consistent.

Quick answer: three core rate relationships

Average speed = total distance ÷ total elapsed time, for the interval the question defines.
Distance = speed × time, for constant-speed motion or a suitable average over a defined interval.
Time = distance ÷ speed, where speed is nonzero and definitions match.

Jump to the explanation you need

One-minute speed diagnostic
Why the 3.6 factor works
Average speed across stages and stops
50-plus original speed clinics
First-error diagnosis
Three-pupil tutorial model
A five-day revision plan
FAQs
Official sources

A 60-second diagnostic

Speed conversion is a ratio of units

one

two

three

Average speed depends on both totals

total

rest

direction

Original rate, speed and unit-conversion clinics

1. Convert km/h to m/s 1

Question. An imaginary vehicle has a stated speed of 18 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 18×1000/3600 = 18/3.6 = 5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 5 m/s by 3.6 to recover 18 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

2. Convert km/h to m/s 2

Question. An imaginary vehicle has a stated speed of 27 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 27×1000/3600 = 27/3.6 = 7.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 7.5 m/s by 3.6 to recover 27 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

3. Convert km/h to m/s 3

Question. An imaginary vehicle has a stated speed of 36 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 36×1000/3600 = 36/3.6 = 10 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 10 m/s by 3.6 to recover 36 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

4. Convert km/h to m/s 4

Question. An imaginary vehicle has a stated speed of 45 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 45×1000/3600 = 45/3.6 = 12.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 12.5 m/s by 3.6 to recover 45 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

5. Convert km/h to m/s 5

Question. An imaginary vehicle has a stated speed of 54 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 54×1000/3600 = 54/3.6 = 15 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 15 m/s by 3.6 to recover 54 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

6. Convert km/h to m/s 6

Question. An imaginary vehicle has a stated speed of 63 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 63×1000/3600 = 63/3.6 = 17.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 17.5 m/s by 3.6 to recover 63 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

7. Convert km/h to m/s 7

Question. An imaginary vehicle has a stated speed of 72 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 72×1000/3600 = 72/3.6 = 20 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 20 m/s by 3.6 to recover 72 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

8. Convert km/h to m/s 8

Question. An imaginary vehicle has a stated speed of 81 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 81×1000/3600 = 81/3.6 = 22.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 22.5 m/s by 3.6 to recover 81 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

9. Convert km/h to m/s 9

Question. An imaginary vehicle has a stated speed of 90 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 90×1000/3600 = 90/3.6 = 25 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 25 m/s by 3.6 to recover 90 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

10. Convert km/h to m/s 10

Question. An imaginary vehicle has a stated speed of 108 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 108×1000/3600 = 108/3.6 = 30 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 30 m/s by 3.6 to recover 108 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

11. Convert km/h to m/s 11

Question. An imaginary vehicle has a stated speed of 144 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 144×1000/3600 = 144/3.6 = 40 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 40 m/s by 3.6 to recover 144 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

12. Convert km/h to m/s 12

Question. An imaginary vehicle has a stated speed of 9 km/h. Convert to metres per second.

Work it through. One kilometre is 1000 m and one hour is 3600 s. Therefore 9×1000/3600 = 9/3.6 = 2.5 m/s.

First wrong step to avoid. Multiplying by 3.6 is the wrong direction for km/h → m/s. A conversion of units must preserve the speed’s physical size even though its numeral changes.

Check. Multiply the answer 2.5 m/s by 3.6 to recover 9 km/h. Note that the conversion describes a rate, not the distance travelled in a given journey.

13. Convert m/s to km/h 1

Question. A fictional moving object travels at 2.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 2.5×3.6 = 9 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 9 km/h by 3.6 to recover 2.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 2.5 m/s gives 50 metres. Compute the same distance using 9 km/h and time 20/3600 hours; the two methods must agree.

14. Convert m/s to km/h 2

Question. A fictional moving object travels at 5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 5×3.6 = 18 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 18 km/h by 3.6 to recover 5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 5 m/s gives 100 metres. Compute the same distance using 18 km/h and time 20/3600 hours; the two methods must agree.

15. Convert m/s to km/h 3

Question. A fictional moving object travels at 7.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 7.5×3.6 = 27 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 27 km/h by 3.6 to recover 7.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 7.5 m/s gives 150 metres. Compute the same distance using 27 km/h and time 20/3600 hours; the two methods must agree.

16. Convert m/s to km/h 4

Question. A fictional moving object travels at 10 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 10×3.6 = 36 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 36 km/h by 3.6 to recover 10 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 10 m/s gives 200 metres. Compute the same distance using 36 km/h and time 20/3600 hours; the two methods must agree.

17. Convert m/s to km/h 5

Question. A fictional moving object travels at 12.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 12.5×3.6 = 45 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 45 km/h by 3.6 to recover 12.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 12.5 m/s gives 250 metres. Compute the same distance using 45 km/h and time 20/3600 hours; the two methods must agree.

18. Convert m/s to km/h 6

Question. A fictional moving object travels at 15 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 15×3.6 = 54 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 54 km/h by 3.6 to recover 15 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 15 m/s gives 300 metres. Compute the same distance using 54 km/h and time 20/3600 hours; the two methods must agree.

19. Convert m/s to km/h 7

Question. A fictional moving object travels at 17.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 17.5×3.6 = 63 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 63 km/h by 3.6 to recover 17.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 17.5 m/s gives 350 metres. Compute the same distance using 63 km/h and time 20/3600 hours; the two methods must agree.

20. Convert m/s to km/h 8

Question. A fictional moving object travels at 20 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 20×3.6 = 72 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 72 km/h by 3.6 to recover 20 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 20 m/s gives 400 metres. Compute the same distance using 72 km/h and time 20/3600 hours; the two methods must agree.

21. Convert m/s to km/h 9

Question. A fictional moving object travels at 22.5 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 22.5×3.6 = 81 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 81 km/h by 3.6 to recover 22.5 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 22.5 m/s gives 450 metres. Compute the same distance using 81 km/h and time 20/3600 hours; the two methods must agree.

22. Convert m/s to km/h 10

Question. A fictional moving object travels at 25 m/s. What is the same speed in km/h?

Work it through. Multiply by 3600 seconds per hour and divide by 1000 metres per kilometre, a net factor of 3.6. 25×3.6 = 90 km/h.

First wrong step to avoid. Dividing by 3.6 goes from km/h to m/s, not from m/s to km/h. Do not apply the same button for both conversion directions.

Check. Divide 90 km/h by 3.6 to recover 25 m/s. The answer refers to the same physical rate.

Transfer. For a uniform 20-second interval, a speed of 25 m/s gives 500 metres. Compute the same distance using 90 km/h and time 20/3600 hours; the two methods must agree.

23. Find average speed with minutes 1

Question. A hypothetical journey covers 24 km in 30 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 30 min to 0.5 h. Average speed is distance ÷ time = 24 ÷ (30/60) = 48 km/h.

First wrong step to avoid. Dividing 24 by 30 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 0.5 h reproduces 24 km, up to any displayed rounding. The units km/h × h simplify to km.

24. Find average speed with minutes 2

Question. A hypothetical journey covers 45 km in 45 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 45 min to 0.75 h. Average speed is distance ÷ time = 45 ÷ (45/60) = 60 km/h.

First wrong step to avoid. Dividing 45 by 45 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 60 km/h multiplied by 0.75 h reproduces 45 km, up to any displayed rounding. The units km/h × h simplify to km.

25. Find average speed with minutes 3

Question. A hypothetical journey covers 60 km in 75 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 75 min to 1.25 h. Average speed is distance ÷ time = 60 ÷ (75/60) = 48 km/h.

First wrong step to avoid. Dividing 60 by 75 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 1.25 h reproduces 60 km, up to any displayed rounding. The units km/h × h simplify to km.

26. Find average speed with minutes 4

Question. A hypothetical journey covers 27 km in 20 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 20 min to 0.33333 h. Average speed is distance ÷ time = 27 ÷ (20/60) = 81 km/h.

First wrong step to avoid. Dividing 27 by 20 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 81 km/h multiplied by 0.33333 h reproduces 27 km, up to any displayed rounding. The units km/h × h simplify to km.

27. Find average speed with minutes 5

Question. A hypothetical journey covers 36 km in 50 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 50 min to 0.83333 h. Average speed is distance ÷ time = 36 ÷ (50/60) = 43.2 km/h.

First wrong step to avoid. Dividing 36 by 50 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 43.2 km/h multiplied by 0.83333 h reproduces 36 km, up to any displayed rounding. The units km/h × h simplify to km.

28. Find average speed with minutes 6

Question. A hypothetical journey covers 105 km in 90 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 90 min to 1.5 h. Average speed is distance ÷ time = 105 ÷ (90/60) = 70 km/h.

First wrong step to avoid. Dividing 105 by 90 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 70 km/h multiplied by 1.5 h reproduces 105 km, up to any displayed rounding. The units km/h × h simplify to km.

29. Find average speed with minutes 7

Question. A hypothetical journey covers 12 km in 15 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 15 min to 0.25 h. Average speed is distance ÷ time = 12 ÷ (15/60) = 48 km/h.

First wrong step to avoid. Dividing 12 by 15 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 48 km/h multiplied by 0.25 h reproduces 12 km, up to any displayed rounding. The units km/h × h simplify to km.

30. Find average speed with minutes 8

Question. A hypothetical journey covers 96 km in 80 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 80 min to 1.3333 h. Average speed is distance ÷ time = 96 ÷ (80/60) = 72 km/h.

First wrong step to avoid. Dividing 96 by 80 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 72 km/h multiplied by 1.3333 h reproduces 96 km, up to any displayed rounding. The units km/h × h simplify to km.

31. Find average speed with minutes 9

Question. A hypothetical journey covers 14 km in 35 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 35 min to 0.58333 h. Average speed is distance ÷ time = 14 ÷ (35/60) = 24 km/h.

First wrong step to avoid. Dividing 14 by 35 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 24 km/h multiplied by 0.58333 h reproduces 14 km, up to any displayed rounding. The units km/h × h simplify to km.

32. Find average speed with minutes 10

Question. A hypothetical journey covers 33 km in 22 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 22 min to 0.36667 h. Average speed is distance ÷ time = 33 ÷ (22/60) = 90 km/h.

First wrong step to avoid. Dividing 33 by 22 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 90 km/h multiplied by 0.36667 h reproduces 33 km, up to any displayed rounding. The units km/h × h simplify to km.

33. Find average speed with minutes 11

Question. A hypothetical journey covers 75 km in 50 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 50 min to 0.83333 h. Average speed is distance ÷ time = 75 ÷ (50/60) = 90 km/h.

First wrong step to avoid. Dividing 75 by 50 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 90 km/h multiplied by 0.83333 h reproduces 75 km, up to any displayed rounding. The units km/h × h simplify to km.

34. Find average speed with minutes 12

Question. A hypothetical journey covers 126 km in 105 minutes. Find average speed in km/h, including the stated elapsed time.

Work it through. Convert 105 min to 1.75 h. Average speed is distance ÷ time = 126 ÷ (105/60) = 72 km/h.

First wrong step to avoid. Dividing 126 by 105 directly gives kilometres per minute, not kilometres per hour. A unit mismatch can hide behind a plausible-looking number.

Check. 72 km/h multiplied by 1.75 h reproduces 126 km, up to any displayed rounding. The units km/h × h simplify to km.

35. Use total distance and total time 1

Question. On an invented two-stage journey, stage one covers 60 km in 1 h, and stage two covers 60 km in 2 h. Find overall average speed.

Work it through. Total distance is 60+60=120 km. Total elapsed time is 1+2=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 30 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

36. Use total distance and total time 2

Question. On an invented two-stage journey, stage one covers 30 km in 0.5 h, and stage two covers 90 km in 1.5 h. Find overall average speed.

Work it through. Total distance is 30+90=120 km. Total elapsed time is 0.5+1.5=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

37. Use total distance and total time 3

Question. On an invented two-stage journey, stage one covers 80 km in 2 h, and stage two covers 40 km in 0.5 h. Find overall average speed.

Work it through. Total distance is 80+40=120 km. Total elapsed time is 2+0.5=2.5 h. Divide totals: 120/2.5=48 km/h.

Check. 48×2.5≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 40 and 80 km/h. Compare them with the overall 48. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

38. Use total distance and total time 4

Question. On an invented two-stage journey, stage one covers 70 km in 1 h, and stage two covers 30 km in 1.5 h. Find overall average speed.

Work it through. Total distance is 70+30=100 km. Total elapsed time is 1+1.5=2.5 h. Divide totals: 100/2.5=40 km/h.

Check. 40×2.5≈100 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 70 and 20 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

39. Use total distance and total time 5

Question. On an invented two-stage journey, stage one covers 45 km in 0.75 h, and stage two covers 75 km in 1.25 h. Find overall average speed.

Work it through. Total distance is 45+75=120 km. Total elapsed time is 0.75+1.25=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

40. Use total distance and total time 6

Question. On an invented two-stage journey, stage one covers 20 km in 0.5 h, and stage two covers 100 km in 2.5 h. Find overall average speed.

Work it through. Total distance is 20+100=120 km. Total elapsed time is 0.5+2.5=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 40 and 40 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

41. Use total distance and total time 7

Question. On an invented two-stage journey, stage one covers 48 km in 1 h, and stage two covers 72 km in 2 h. Find overall average speed.

Work it through. Total distance is 48+72=120 km. Total elapsed time is 1+2=3 h. Divide totals: 120/3=40 km/h.

Check. 40×3≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 48 and 36 km/h. Compare them with the overall 40. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

42. Use total distance and total time 8

Question. On an invented two-stage journey, stage one covers 50 km in 1.25 h, and stage two covers 90 km in 1.75 h. Find overall average speed.

Work it through. Total distance is 50+90=140 km. Total elapsed time is 1.25+1.75=3 h. Divide totals: 140/3=46.667 km/h (rounded as displayed).

Check. 46.667×3≈140 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

43. Use total distance and total time 9

Question. On an invented two-stage journey, stage one covers 90 km in 1.5 h, and stage two covers 30 km in 0.5 h. Find overall average speed.

Work it through. Total distance is 90+30=120 km. Total elapsed time is 1.5+0.5=2 h. Divide totals: 120/2=60 km/h.

Check. 60×2≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 60 and 60 km/h. Compare them with the overall 60. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

44. Use total distance and total time 10

Question. On an invented two-stage journey, stage one covers 36 km in 0.75 h, and stage two covers 84 km in 1.75 h. Find overall average speed.

Work it through. Total distance is 36+84=120 km. Total elapsed time is 0.75+1.75=2.5 h. Divide totals: 120/2.5=48 km/h.

Check. 48×2.5≈120 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 48 and 48 km/h. Compare them with the overall 48. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

45. Use total distance and total time 11

Question. On an invented two-stage journey, stage one covers 65 km in 1.3 h, and stage two covers 35 km in 0.7 h. Find overall average speed.

Work it through. Total distance is 65+35=100 km. Total elapsed time is 1.3+0.7=2 h. Divide totals: 100/2=50 km/h.

Check. 50×2≈100 km. This test recovers the total distance, with a small difference possible if the displayed speed was rounded.

Transfer. Compute the individual stage speeds 50 and 50 km/h. Compare them with the overall 50. State why a simple midpoint of the two stage speeds is not guaranteed to equal the journey average.

46. Reason about a rate or elapsed time 1

Question. An office printer makes 144 pages in 12 minutes. What is its average pages per minute?

Work it through. 144 ÷ 12 = 12 pages/min.

First wrong step to avoid. Reading 12 as minutes per page, which reverses the rate.

Check. At this rate 5 minutes produces 60 pages.

47. Reason about a rate or elapsed time 2

Question. A tap adds 48 litres in eight minutes. What is its average flow?

Work it through. 48 ÷ 8 = 6 L/min.

First wrong step to avoid. Writing 6 min/L rather than litres per minute.

Check. Check 6 L/min × 8 min = 48 L.

48. Reason about a rate or elapsed time 3

Question. A machine makes 84 labels in seven minutes. How long for 132 labels at constant rate?

Work it through. Its rate is 84/7=12 labels/min. Required time is 132/12 = 11 minutes.

First wrong step to avoid. Multiplying labels by the rate rather than dividing to find time.

Check. 12 labels/min × 11 min = 132 labels.

49. Reason about a rate or elapsed time 4

Question. A student reads 24 pages in 30 minutes at a constant pace. What is the page rate?

Work it through. Rate=24/30=0.8 pages/min, or 48 pages/hour.

First wrong step to avoid. Reporting 1.25 pages/min, which is the minutes per page instead.

Check. Check 0.8×30=24 pages.

50. Reason about a rate or elapsed time 5

Question. A fictional pump moves 90 L in six minutes. How long for 225 L at the same rate?

Work it through. Rate=90/6=15 L/min. Time=225/15=15 minutes.

First wrong step to avoid. Using 225×15 and obtaining an amount with incorrect units.

Check. 15 L/min × 15 min = 225 L.

51. Reason about a rate or elapsed time 6

Question. Convert 2.5 hours to hours and minutes.

Work it through. 0.5 h is thirty minutes, so 2 h 30 min.

First wrong step to avoid. Reading 2.5 as two hours five minutes.

Check. 2 + 30/60 = 2.5 hours.

52. Reason about a rate or elapsed time 7

Question. Convert one hour 12 minutes to decimal hours.

Work it through. 12/60 = 0.2 hour, so total is 1.2 hours.

First wrong step to avoid. Writing 1.12 hours by treating minutes as decimal hundredths.

Check. 1.2×60=72 minutes.

53. Reason about a rate or elapsed time 8

Question. A car covers 150 km at uniform 50 km/h. Find duration.

Work it through. Time=distance/speed=150/50=3 h.

First wrong step to avoid. Multiplying speed and distance to find time.

Check. 50 km/h × 3 h = 150 km.

54. Reason about a rate or elapsed time 9

Question. A cyclist travels at constant 18 km/h for 40 minutes. Find distance.

Work it through. 40 minutes is 2/3 hour. Distance=18×(2/3)=12 km.

First wrong step to avoid. Using 18×40 as if minutes were hours.

Check. 12 km/(2/3 h)=18 km/h.

55. Reason about a rate or elapsed time 10

Question. A journey covers 30 km at 60 km/h, then includes a 30-minute stop. Find average speed for the full elapsed hour.

Work it through. Moving time is 0.5 h and stopped time is 0.5 h. Total elapsed is one hour, so average speed=30 km/h.

First wrong step to avoid. Ignoring stationary time and reporting 60 km/h for the whole elapsed interval.

Check. 30 km÷1 h=30 km/h; be clear about what the question calls elapsed time.

56. Reason about a rate or elapsed time 11

Question. A walker covers 3 km in 30 minutes and then rests 15 minutes. Find average speed across the entire interval.

Work it through. Distance=3 km; elapsed time=45 min=0.75 h, so speed=3/0.75=4 km/h.

First wrong step to avoid. Using only walking time when the problem includes the rest in the requested interval.

Check. 3 km÷0.75 h=4 km/h.

57. Reason about a rate or elapsed time 12

Question. Outward distance 60 km at 60 km/h, return distance 60 km at 30 km/h. Find full-trip average speed.

Work it through. Outward time=1 h, return time=2 h, total distance=120 km and total time=3 h, so average=40 km/h.

First wrong step to avoid. Averaging 60 and 30 to 45 km/h is wrong because journey times differ.

Check. 40×3=120 km; this is the unequal-time equal-distance trap.

58. Reason about a rate or elapsed time 13

Question. For the same fixed 180-km journey, compare 60 km/h with 90 km/h travel times.

Work it through. At 60 km/h, time=180/60=3 h. At 90 km/h, time=180/90=2 h. Faster travel saves one hour in the ideal constant-speed model.

First wrong step to avoid. Calling the time saving 30 minutes because the speed rose by 30 km/h.

Check. Check both speed×time products equal 180 km.

59. Reason about a rate or elapsed time 14

Question. A hypothetical conveyor carries 360 parts in 15 minutes. Find parts per hour.

Work it through. Rate=360/15=24 parts/min, or 24×60=1440 parts/hour.

First wrong step to avoid. Dividing by 60 when converting a per-minute count into a per-hour count.

Check. 1440/60=24 parts/min.

60. Reason about a rate or elapsed time 15

Question. A tank holds 240 L and fills at a constant 20 L/min. How long to fill from empty?

Work it through. Time=240/20=12 minutes.

First wrong step to avoid. Multiplying 240×20, which has units L²/min.

Check. 20 L/min × 12 min = 240 L.

61. Reason about a rate or elapsed time 16

Question. A vehicle travels at 5 m/s for 12 seconds. Find its distance.

Work it through. Distance=5×12=60 m.

First wrong step to avoid. Giving 60 m/s when the requested quantity is distance.

Check. 60m/12s=5m/s.

62. Reason about a rate or elapsed time 17

Question. A student says 72 km/h equals 72 m/s. Explain the error.

Work it through. The numerical value changes under unit conversion: 72 km/h ÷ 3.6 = 20 m/s.

First wrong step to avoid. Assuming two units of speed use the same number.

Check. 20 m/s is 72 km/h because 20×3.6=72.

63. Reason about a rate or elapsed time 18

Question. A 120-km trip has a 90-minute moving period and a 30-minute stop. What is average speed including stop?

Work it through. Total elapsed=120 min=2 h, so average speed=60 km/h.

First wrong step to avoid. Dividing by 1.5 h instead of the full two hours requested.

Check. 60 km/h×2 h=120 km.

64. Reason about a rate or elapsed time 19

Question. A rate is 36 km/h. How far is travelled in 15 minutes at constant speed?

Work it through. 15 min=0.25 h; distance=36×0.25=9 km.

First wrong step to avoid. Treating fifteen minutes as 0.15 hour.

Check. 9 km/0.25 h=36 km/h.

65. Reason about a rate or elapsed time 20

Question. Two journeys have equal distance but different average speeds. Which one takes longer?

Work it through. At fixed distance, time=distance/speed, so the one with lower average speed takes longer, assuming the same definition of elapsed time.

First wrong step to avoid. Concluding that a larger km/h number means larger hours.

Check. Use 100 km at 50 km/h (2 h) and 100 km at 100 km/h (1 h).

66. Reason about a rate or elapsed time 21

Question. A numerical answer of 3 may represent different units. How can a pupil decide?

Work it through. Read the requested quantity and analyse units: km÷(km/h) gives hours; km÷h gives km/h; km/h×h gives kilometres.

First wrong step to avoid. Writing only 3 without units because the arithmetic looks tidy.

Check. Show the cancellation in each case, then state the correct noun.

Five typical speed mistakes and their repairs

error1

error2

error3

error4

error5

How an illustrative three-pupil tutorial might work

First 10 minutes: retrieve metric and time conversions without a calculator.
Next 20 minutes: derive the speed formulas from units and convert both km/h and m/s.
Next 25 minutes: individual mixed speed and time problems with first-line feedback.
Next 15 minutes: compare stage-speed arithmetic with whole-trip average speed.
Next 10 minutes: unseen mixed rates including print output or liquid flow.
Final 10 minutes: recheck units and plan short retrieval practice.

Five short home sessions

Monday: derive the 3.6 conversion factor from 1000 and 3600, then convert six speeds both ways.
Tuesday: convert minutes and mixed hours into decimal hours and back.
Wednesday: solve two questions each for distance, speed and duration.
Thursday: find total distance and elapsed time for two-stage journeys; include one with a stop.
Friday: practise non-travel rates, then re-solve the week’s first mistaken calculation without viewing the answer.

G1 subject level and the published 2027 SEC syllabus

Frequently asked questions

faq1

Because one kilometre is 1000 metres and one hour is 3600 seconds; 1000/3600=1/3.6.

faq2

faq3

It counts when the question defines total elapsed journey time to include that stop. Read the requested interval carefully.

faq4

The stages may have unequal durations or distances. The whole-trip average comes from total distance and total time; an unweighted mean can be wrong.

faq5

The underlying concept is the same: output divided by time. Preserve the actual units such as pages/min or L/min.

faq6

Yes. It is explicitly listed in the MOE Secondary Two G1 N4 content. School assessment dates and emphasis vary.

Secondary 2 G1 Mathematics Tutor Bukit Timah | Average Speed and Rate Conversions

Official references and reader note

Official references and reader note

G1 subject level and the published 2027 SEC syllabus

Frequently asked questions

faq1

faq2

faq3

faq4

faq5

faq6

Related Secondary 2 G1 Mathematics guides

Official references and reader note

G1 subject level and the published 2027 SEC syllabus

Frequently asked questions

faq1

faq2

faq3

faq4

faq5

faq6

Related Secondary 2 G1 Mathematics guides

Official references and reader note

Five short home sessions

G1 subject level and the published 2027 SEC syllabus

Frequently asked questions

faq1

faq2

faq3

faq4

faq5

faq6

Related Secondary 2 G1 Mathematics guides

Official references and reader note

Five short home sessions

G1 subject level and the published 2027 SEC syllabus

Frequently asked questions

faq1

faq2

faq3

faq4

faq5

faq6

Related Secondary 2 G1 Mathematics guides

Official references and reader note

A 60-second diagnostic

Speed conversion is a ratio of units

one

two

three

Average speed depends on both totals

total

rest

direction

Original rate, speed and unit-conversion clinics

1. Convert km/h to m/s 1

2. Convert km/h to m/s 2

3. Convert km/h to m/s 3

4. Convert km/h to m/s 4

5. Convert km/h to m/s 5

6. Convert km/h to m/s 6

7. Convert km/h to m/s 7

8. Convert km/h to m/s 8

9. Convert km/h to m/s 9

10. Convert km/h to m/s 10

11. Convert km/h to m/s 11

12. Convert km/h to m/s 12

13. Convert m/s to km/h 1

14. Convert m/s to km/h 2

15. Convert m/s to km/h 3

16. Convert m/s to km/h 4

17. Convert m/s to km/h 5

18. Convert m/s to km/h 6

19. Convert m/s to km/h 7

20. Convert m/s to km/h 8

21. Convert m/s to km/h 9

22. Convert m/s to km/h 10

23. Find average speed with minutes 1

24. Find average speed with minutes 2

25. Find average speed with minutes 3