Draw Pie Charts

When we are drawing a pie chart, we will normally be given a frequency table and have to link the frequencies to the angles we are going to draw.

 

Example:

Here are the makes of some cars.

Draw a pie chart to show this data.

 

Make	Ford	Nissan	BMW	Mini	Vauxhall
Frequency	4	5	2	3	6

 

Step 1: Find out what the total frequency is.

If we add the frequencies together, we get 4 + 5 + 2 + 3 + 6 = 20

This means that our pie chart has to represent 20 cars in total.

 

Step 2: Work out what each car is worth as an angle.

All circles add up to 360°. If we split this into 20 parts:

360 ÷ 20 = 18°

 

Step 3: Work out what each category is worth.

There are four Fords and each one is worth 18°. This means the Ford category is worth 4 x 18 = 72°

We can do this for all the other categories:

 

Make	Ford	Nissan	BMW	Mini	Vauxhall
Frequency	4	5	2	3	6
Angle	72	90	36	54	108

 

We can now check we have done this correctly by adding up all the angles. We should always get 360.

 

Step 4: Draw the angles onto a pie chart and label the sectors.

You can either give a key, or write the names in the sectors. It doesn't matter which you do, you'll still get the same marks either way.

 

 

Let's move on to some questions now.