Pie Charts

1
Pie Charts
2
Why a Pie Chart?

• Very visual
• Easy to read
• Slices show clearly how the data is distributed

3
Data for a Pie Chart
Favourite Drink Frequency
Milk 7
Orange 9
Cola 13
Water 6
Tea 2
Other 3

• Usually given in a table format
• This data was obtained from a class survey on
  Favourite Drinks

How many people said they preferred this drink
These are the answers given
Other allows for unexpected answers
4
1 Work out the slices
Favourite Drink Frequency
Milk 7
Orange 9
Cola 13
Water 6
Tea 2
Other 3
We need to calculate the size of each slice
in the pie chart
40 people responded to the survey
If very person had their own slice, each would
get the same
of the circle
X 360º
9º
Total 40
5
If 1 person is 9º
Angle






Favourite Drink Frequency
Milk 7
Orange 9
Cola 13
Water 6
Tea 2
Other 3
7 x 9
63º
81º
9 x 9
13 x 9
117º
6 x 9
54º
2 x 9
18º
3 x 9
27º
Total 360º
6
2 Draw the Pie Chart
x
Mark a centre for the Pie Chart
Draw a circle with centre on the mark
Use compasses
Or draw around an Angle Measure
7
2 Draw the Pie Chart
Draw line vertically from centre to circumference
Draw LARGEST slice first i.e. Cola 117º
Cola
x
Label the slice Cola
Do not enter the angle or the frequency!
8
2 Draw the Pie Chart
Draw NEXT LARGEST slice i.e. Orange 81º
Turn Protractor so that 0º marker is at the
end of line just drawn
Cola
Orange
9
2 Draw the Pie Chart
Then Milk 63º
Cola
Milk
Orange
10
2 Draw the Pie Chart
Then Water 54º
Water
Cola
Milk
Orange
11
2 Draw the Pie Chart
Then Other 27º
Other
Water
Cola
Milk
Orange
12
2 Draw the Pie Chart
The LAST slice is already drawn just check
it Tea 18º
Tea
Other
Water
Give the Pie Chart its Title
Cola
Milk
Orange
Class 7As Favourite Drink
Remove the small guide marks carefully