In KS3 Maths you'll do a lot of work on data handling. One part of data handling is representing the information you have in the form of graphs, tables or charts. This quiz looks in detail at one of these methods - pie charts.

A pie chart is a good way to illustrate how a data set is distributed over its different categories. Each category is represented by a 'slice' of the pie and the bigger the 'slice' the more important that category is. Imagine that you ask 100 people to name their favourite film genre. 50 say comedy but only 5 say romance. Comedy would take up one half of your pie chart whilst romance would only be one tenth. The hard part comes in converting these fractions into degrees.

Like all circles, pie charts contain 360^{o}. That means that every 1% takes up 3.6^{o}. In our example, comedy would take up 180^{o} on the pie chart and romance would be 36^{o}. It's quite simple once you've got the hang of it. Try this quiz to see how well you understand pie charts.

1.

Each 'slice' of a pie chart is what part of a circle?

Sector

Segment

Sequence

Series

A sector is a portion of a circle enclosed by two radii and an arc

2.

The size of each 'slice' of pie is measured by its .......

accuracy

amplitude

angle

arc

The larger the angle, the more important the category

3.

The total of the pie chart angles should be .......

90°

180°

270°

360°

Just as in all circles

4.

In a percentage pie chart, what angle represents 10% of the data?

15°

30°

36°

72°

10% is 1/10. One tenth of the pie chart is 360 / 10 = 36

5.

What fraction of a pie chart showing the favourite TV soaps of 400 people, represents the 80 people who chose Eastenders?

1/8

1/5

1/4

1/2

80 / 400 = 1/5

6.

In the TV soaps survey 150 people chose Coronation Street. What pie chart angle represents this group?

120°

125°

130°

135°

150 / 400 = 3/8. To find 3/8 of 360° divide by 8 then multiply by 3. (360 / 8) x 3 = 45 x 3

7.

In a pie chart showing the sports played by 1,000 boys, a 45° sector is labelled 'no regular sport'. How many boys does this represent?

45

125

200

720

45° is 1/8 of the pie chart so represents 1/8 of the 1,000 boys. 1000 / 8 = 125

8.

What percentage of the boys said they took part in no regular sport?

10%

12^{1}⁄_{2}%

25%

33^{1}⁄_{3}%

It's helpful to remember some common percentages and their fraction equivalents, e.g. 1/8 = 12^{1}⁄_{2}%

9.

The sector labelled 'football' is more than half the pie chart so the number of boys who play football is more than .......

180

360

500

750

Half of 1,000 is 500. You cannot say how much more than 500 unless you know the size of the pie chart angle

10.

Ten boys said they played tennis. To the nearest degree, what pie chart angle represents tennis?

4°

5°

14°

15°

10 is 1% of the total. To find 1% you divide by 100. 360 / 100 = 3.6