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.
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 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:
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.