Drawing a pie chart
Look at this record of traffic travelling down a particular road.
Traffic Survey 31 January 2008
| Type of vehicle | Number of vehicles |
|---|---|
| Cars | 140 |
| Motorbikes | 70 |
| Vans | 55 |
| Buses | 5 |
| Total vehicles | 270 |
To draw a pie chart, we need to represent each part of the data as a proportion of 360, because there are 360 degrees in a circle.
For example, if 55 out of 270 vehicles are vans, we will represent this on the circle as a segment with an angle of: (55/270) x 360 = 73 degrees.
This will give the following results:
Traffic Survey 31 January 2008
| Type of vehicle | Number of vehicles | Calculation | Degrees of a circle |
|---|---|---|---|
| Cars | 140 | (140/270) x 360 | = 187 |
| Motorbikes | 70 | (70/270) x 360 | = 93 |
| Vans | 55 | (55/270) x 360 | = 73 |
| Buses | 5 | (5/270) x 360 | = 7 |
This data is represented on the pie chart below.
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