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.
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 our pie chart has to represent 20 cars in total.
Step 2: Work out what each car is worth as an angle.
All circles have 360°. If we split this into 20 parts
360 ÷ 20 = 18°
Step 3: Work out what each category is worth
There are 4 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 to get...
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.
I always like giving a key instead of writing the names in the sectors. It doesn't matter which you do, you'll still get the same marks either way.