Pie-chart help. Harder examples on working out the angles in a pie-chart.

I will go through some harder examples on drawing pie-charts in this article.

Harder Pie-Chart Example 1

Work out all the angles needed to draw a pie-chart on this survey about favourite sports.

173 said football

305 said baseball

220 said athletics

22 said other

173 + 305 + 220 + 22 = 720

360 ÷ 720 = 0.5

So this tells you that 1 person on the pie-chart is worth 1/2⁰

All you need to do now is times the number of people who voted each sport by 1/2⁰.

Football = 173 × 0.5 = 86.5⁰

Baseball = 305 × 0.5 = 152.5⁰

Athletics = 220 × 0.5 = 110⁰

Other = 22 × 0.5 = 11⁰

Finally check that these add to 360⁰ before you draw out the pie-chart.

86.5 + 152.5 + 110⁰ + 11⁰ = 360⁰

Harder Pie-Chart Example 2

In this example on drawing a pie-chart you will find that the total amount doesn’t divide exactly into 360⁰.

Work out all the angles needed to draw a pie-chart on this survey about favourite colours.

37 said blue

65 said red

14 said green

2 said other

37 + 65 + 14 + 2 = 118

360 ÷ 118 = 3.05⁰ (to 3 significant figures).

Don’t round this number off to a lower degree of accuracy as this will affect your angles which you are going to calculate next. 3 significant figures will work well.

So this tells you that 1 person on the pie-chart is worth 3.05⁰

All you need to do now is times the number of people who voted each colour by 3.05⁰.

Blue= 37 × 3.05 = 113⁰

Red = 65 × 3.055 = 198⁰

Green = 14 × 3.05 = 43⁰

Other = 2 × 3.05 = 6⁰

Notice I’ve rounded all the angles to the nearest whole degree.

Finally check that these add to 360⁰ before you draw out the pie-chart.

113 + 198 + 43 + 6 = 360⁰

Sometimes this might be 1 degree out due to rounding off the angles to the nearest whole. But you will don’t have to worry about this too much as this will be barely obvious once your pie-chart is drawn.

For some easier examples on drawing pie-charts click here.

Or if you need some help on the stages involved in drawing a pie-chart then click here.