• Pie chart– Used for data that can be counted, used to

compare individual ‘bits’ of data with the whole.

– The whole circle represents all the data.– Each sector represents one ‘bit’ of

information.

Flavour Number (n)

Strawberry 16

Orange 5

Peach 9

Blackberry 4

Other 11

Pie chartThis shows the flavours of yoghurt preferred by 45 students

You are required to draw a Pie Chart to present this information.

You will need to extend the table to be able to calculate the angles.

11Other

4Blackberry

9Peach

5Orange

16Strawberry

Number (n)

Flavour

Totals

n

Total nAngle Rounded

Angle

The angles are calculated by multiplying the respective numbers in column 3 by 360o

This last column is only required IF the angles in the previous column are not whole numbers

88o0.24444

11Other

32o0.08889

4Blackberry

72o0.29Peach

40o0.11111

5Orange

128o0.35556

16Strawberry

Col 3 x 360Number (n)

Flavour n

Total n

360o1.0000

45Totals

It is important to check that the totals of the last two columns add up to 1.0000 and 360o, as this ensures that any errors can be recognised and dealt with.

Another important thing to remember is that IF you have decimal angles and you round them, DO SO CAREFULLY and recheck that the rounded angle add up to 360. You may need to adjust!!!

Flavours of yoghurt

16

59

4

11Straw berry

Orange

Peach

Blackberry

Other

Make sure you measure ALL the angles carefully, DO NOT assume the last angle to be correct… MEASURE IT !!!!

A key is important OR you can label the individual sectors with the NAMES of the “bits”.

Now you try some questions

BIG textbook

p 413 – 414 Questions 2, 3, 4 and 6

p 415 – 416 Questions 1, 3, 5, 7

Interpreting Pie Charts

Sometimes you may be given a completed pie chart and asked to interpret the information.

The pie chart on the left shows the heights (in cm) of 30 pupils in a class.

              

Which group contains the most people?

151-160cm

How many people are in

the group 121-130cm?

3 If you had a problem, remember

that 36° is one-tenth of 360°, so one-tenth of the people are in this

group. You may need to

measure the angles with a

protractor first!!!