Creating and Understanding Pie

Charts

What is a Pie Chart?

A pie chart is a circular chart (pie-shaped); it is split into segments to show percentages or the relative contributions of categories of data.

Survey of female hair colour

Red7%

Brunette39%

Blonde47%

Multi- coloured

7%

How do I draw a pie chart?Step 1

1. Decide on the total number of categories. In other words, identify the categories that you will use.

2. Collect the data so the number per category can be counted (Frequency Table)

Brand Name Tally FrequencyDaz |||| |||| |||| |||| |||| |||| |||| |||| 40

Ariel |||| |||| |||| |||| |||| |||| |||| |||| |||| |||| |||| |||| 60

Bold |||| |||| |||| |||| |||| |||| |||| |||| |||| |||| 50

Fairy |||| |||| |||| |||| |||| 30

Other |||| |||| |||| |||| 20

TOTAL 200

How do I draw a pie chart?Step 2

Brand Name

Units sold / year in 106 Degree Share

Daz 40 x 360 = 72o

Ariel 60 x 360 = 108o

Bold 50 x 360 = 90o

Fairy 30 x 360 = 54o

Other 20 x 360 = 36o

Total 200 Total = 360o

To calculate degree share, you need to divide the share that the category has by the total units and then multiply by 360 (there are 360 degrees (°) in a circle).

40

200

60

20050

200

30

200

20

200

How do I draw a pie chart?Step 3 – Drawing the chart

1st Draw a Circle With a protractor measure 72o Mark this angle and draw a line from the centre to the mark

Turn the protractor so that the zero is now on this line

Now measure 108oNow measure 90o

And finally 54o

You should now be left with 36o

Again, turn the protractor so that zero is now on this line

Again, turn the protractor

Lightly, draw a vertical line through the centre

Please note that due to the limitations of the software some measurements on this

screen are not totally accurate.

How do I draw a pie chart?Step4It may be necessary to work

out the percentage and include this in the labelling. How would we do this?

Brand Name

Units sold /

year in 106

% age

Daz 40(40 ÷ 200) x 100

= 20%

Ariel 60(60 ÷ 200) x 100

= 30%

Bold 50(50 ÷ 200) x 100

= 25%

Fairy 30(30 ÷ 200) x 100

= 15%

Other 20(20 ÷ 200) x 100

= 10%

Total 200

To calculate degree share, you need to divide the share that the category has by the total units and then multiply by 100 (the whole circle is equal to 100%).

Market share of soap powder brands

Daz20%

Ariel30%

Bold25%

Fairy15%

Other10%

ExercisesUse a pie chart to illustrate the data given below, fully label

the chart and show the percentage value of each sector.

180 FE college students were asked what they intended to do next year.

54 Going to university

40 Staying at college

62 Going into employment

24 No firm intention

Exercises

At a concert, the ages of 115 people were recorded as:

Under 20 15

20 - 29 30

30 - 39 22

40 - 59 24

60 and over 24

Draw a pie chart using this data, give the data labels values in % ages

Thirty people were surveyed in a shopping centre and asked their ages. These are displayed below.

54 41 65 46 66 3732 71 34 73 15 2664 22 54 8 58 4314 57 43 52 24 6843 39 59 35 48 49

a) Draw a tally-frequency table.b) Using the data in your frequency table, construct a table

to calculate the angles in a pie chart.c) draw and fully labelled a pie chart to show the

percentage values.