# 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.

## 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 |

## Question

When 100 people were surveyed as to whether the government should spend more money to prevent wildlife smuggling, the responses were:

- Yes - 34
- No - 45
- Unsure - 21

Draw a pie chart with this information.

## Did You Know That...?

**Democracy** in Ancient Greece where the concept originated was quite different to our contemporary understanding of the term. To be eligible to vote, a person had to be a male born in Athens and over 20 years old. Women and slaves were not permitted to cast their votes.