Pie Charts

Pie Charts are also called Circle Graphs and Sector Graphs. They are best for displaying a small number of discrete categories. A common example is the display of opinion poll results being Yes/No (only two categories).

The procedure for creating a pie chart is:

• Calculate the total.
• Calculate the angle of the circle which is proportional to the sector of the circle, the fraction of the total multiplied by 360 degrees. Round the angle to the nearest whole degree.
• Draw the circle and mark a starting line on the circle. Measure the calculated angle from this starting line and draw the required sector.
• Repeat this process for all categories.
• The total number of degrees does not always add up to 360. This is due to the rounding to the nearest whole degree.
• Ensure that you show all your working as well as the completed circle graph in your answer.

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Example - Wildlife Smuggling in Ecuador

Ecuador in South America has a wide biodiversity of colourful birds, but also spends few government funds to stop wildlife smuggling. Below is a table showing the most commonly smuggled animals, most of whom die before reaching their destination. Draw a pie chart of this data.

SMUGGLED ANIMAL	NUMBER SMUGGLED IN ONE WEEK
Macaw	35
Jaguar	4
Capuchin monkey	64
Spider monkey	47

Answer:

SMUGGLED ANIMAL	NUMBER SMUGGLED IN ONE WEEK	WORKING	ANGLE
Macaw	35	35⁄150 × 360 = 84	84 degrees
Jaguar	4	4⁄150 × 360 = 9.6	10 degrees
Capuchin monkey	64	64⁄150 × 360 = 153.6	154 degrees
Spider monkey	47	47⁄150 × 360 = 112.8	113 degrees
TOTAL	150