Pie Graphs are used when all of the things you are working with can be placed into separate categories.
Pie Graphs are useful to compare.
General Rules
1) Everything you have can be placed into a group / category.
2) No one thing fits into more than one group.

Pie Graphs Use 360 degrees of a
Circle to represent 100%
I nteresting point …
360 divided by 100 = 3.6

Once you have chosen DATA to PIE Graph …..
Step 1 – Build a RAW Table of DATA
This table will have 4 columns
Some Rounding rules
- round percent numbers to one decimal place
- round degrees to the nearest whole number example: class eye colour Raw Data
Category number
Blue
Green
Hazel
Brown
8
12
6
4
TOTAL 30

Next … add a column for percentage and
DO THE MATH

Category number Percent
Blue 8 (8/30)*100 = 26.7
Green
Hazel
12 (12/30)*100 = 40.0
6 (6/30)*100 = 20.0
Brown 4 (4/30)*100 = 13.3
TOTAL 30 100.0

Add the fourth column
- here you calculate degrees from the percent numbers
• In this column take the percentage and multiply by 3.6

Category number Percent
Blue
Degrees
8 (8/30)*100 = 26.7 26.7*3.6= 96
Green
Hazel
Brown
12 (12/30)*100 = 40.0 40.0*3.6= 144
TOTAL 30
6 (6/30)*100 = 20.0 20.0*3.6= 72
4 (4/30)*100 = 13.3 13.3*3.6= 48
100.0 360

In our class, the order in which the slices of the pie get organized will matter.
• In some cases Pie graph slice order seems random.
• In other cases it can be used to show patterns better.

Unless otherwise mentioned … for our geography class
• Draw a pie graph from smallest to largest.
• Start at the 12 o’clock position when drawing
• This leaves all the math rounding error for the last and largest slice.

We will use a Blank Pie Graph that has tick marks every 10 degrees when drawing our PIE GRAPHS.
• The line position will get calculated and the lines can be drawn based on numbers in a second
“organized” table.
• Each tick mark has a number between 0 and 360.
• All tick marks go up by 10 as you go clockwise

270
PIE GRAPHING BLANK
0
90
180

Step 2 – Re-organize original data
- Organize from Smallest to largest
- This Table will also have 4 Columns
- 3 Columns from the previous chart and one new one example: class eye colour Organized Table
Category Percent degrees Line Position
Brown
Hazel
13.3
20.0
48
72
Blue
Green
26.7 96
40 .0
TOTAL 100
144
360

It will identify the exact position
(out of 360 degrees) to draw boundary lines
To calculate … add the thickness of the new pie slice to the previous line position above in the table.
LOOK at the results in the completed table.

Category Percent
Brown 13.3
Hazel
Blue
20.0
degrees
48
Line position
0 + 48 = 48
72 48 + 72 = 120
26.7 96 120 + 96 = 216
Green 40 .0
TOTAL 100
144
360
216 + 144= 360

To Draw and Label Pie Graph Blank
1) Start at The top centre = 0 degrees
2) Identify the correct line position using the 10 degree tick marks to find the
(in this case 48 degrees is the first line).
3) Draw a line from the centre of the pie to the edge at this exact line position.
( you may have to estimate between ticks )

270
0
20
40
The 48 degree line position
50
110
90
180

Find Line position for Line #2 on the pie graph and draw it in Place.
(In this case it is at line position of
120 degrees)

270
20
180
130
110
90
The 120 degree line position

Find Line position for Line #3 on the pie graph and draw it in Place.
In this case it is at line position of 216 degrees

270
180
20
The 48 degree line position
90

Your final product should look something like this