What is a pie chart?
A pie chart is a circle divided into sectors (slices). The whole circle stands for all of the data — that is 100% or 360°. A bigger slice means a bigger part of the group, so we can compare parts just by looking at their sizes.
Reading a pie chart
Half the circle = ½ = 50%. A quarter = ¼ = 25%. To find how many items a slice stands for, multiply the fraction by the total. Because all the slices make one whole, their percentages must add up to 100%.
Key idea
Number in a slice = fraction of the slice × total number.
Worked example
A pie chart shows the favourite fruit of 40 pupils. The apple slice is ¼ of the circle. How many pupils chose apple?
Apple = ¼ × 40 = 40 ÷ 4 = 10 pupils.
If the banana slice is half of the circle, then banana = ½ × 40 = 20 pupils. The two slices together are 10 + 20 = 30, leaving 10 pupils for the other fruits.
Remember
- The whole circle = 100% = 360°.
- Half = 50%, quarter = 25%.
- Multiply the fraction by the total.