A larger sector in a pie chart shows a larger share of that chart’s total. When the charts represent different totals, a larger share can still correspond to fewer people. Convert each sector angle to a fraction of its own total before comparing counts.
The 2027 SEC G3 Mathematics K310 syllabus includes interpreting pie charts. This worked example shows how the answer changes depending on whether you are comparing the number of pupils or the percentage of pupils.
- Find the total for each chart.
- Divide each angle by 360° to get the share.
- Multiply by the corresponding total to find the count.
- Answer in the measure the question requests.
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Read the whole before reading the slice
Suppose two schools use pie charts to show their pupils’ choices of after-school activity. School A surveyed 80 pupils. School B surveyed 150 pupils. A full circle represents all 80 pupils in the first chart and all 150 in the second.
The art sector is 90° in A and 72° in B. The sectors represent one quarter and one fifth of their respective groups.
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Worked example | The smaller sector has the larger count
In School A, the number choosing art is 90/360 × 80 = 20. In School B it is 72/360 × 150 = 30. School B has more pupils choosing art. School A has the greater percentage choosing art, because 25% exceeds 20%.
Keep both statements if asked to compare the charts. A sentence that says “A is higher” leaves the reader guessing whether you mean count or percentage.
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Work backwards from an equal count
At School B, a sector representing the same 20 pupils as School A would measure 20/150 × 360° = 48°. Equal counts take up different angles because the totals are different.
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Frequently asked questions
What if the two totals are the same?
The larger angle represents both a larger share and a larger count. The common total makes those comparisons agree.
What can a parent ask during revision?
Ask the student which chart has more art pupils and which has the larger share. Have them explain how the two answers can differ.