Handling Data

Pie ChartsData (numbers) can be shown much more clearly using charts and graphs.

Monday

Tuesday

Wednesday

Thursday

Friday

0

2

4

6

8

MalesFemales

Handling Data

Pie ChartsOne type of chart very frequently used is a pie chart.

Favourite Colours

BlueRedGreenPurple

Handling Data

Pie ChartsHow do we draw a pie chart so that each sector (slice of pie) is the correct size to show the number?

This is all based on dividing up the number of degrees in a circle (3600) equally first.

Handling Data

Pie ChartsLets start with some data.

A tray of pencils contains the following colours:

Colour of Pencil Number of Pencils

Blue 9

Red 11

Green 7

Yellow 6

Orange 3

Total 36

Handling Data

Pie ChartsThere are 36 pencils in total

How should we divide up the 3600 of a circle to represent all 36 pencils?

If we said 10 represents 1 pencil, how many degrees would be used?

36

Handling Data

Pie Charts

360Only a small part of the whole circle is used.

Handling Data

Pie ChartsIf we said 20 represents 1 pencil, how many degrees would be used?

36

Handling Data

Pie Charts

720

A bit more of the circle is used, but still nowhere near the whole circle.

Handling Data

Pie ChartsWe could keep on increasing the number of degrees represented by one pencil until the whole circle (3600) is used… or we could

Divide 3600 by the 36 pencils. This will tell us that each pencil is represented by 100!

Handling Data

Pie ChartsIf each sector represents 1 pencil, to show the blue pencils we would need to colour in 9 of them blue.