# Drawing, reading and interpreting sector (pie) graphs

## Sector (pie) graphs

**Sector graphs** are also called pie charts or pie graphs. Sector graphs are like divided bar graphs. Both types of graphs show a total amount split into proportional parts. Sector graphs use a circle. Each quantity is graphed as a sector of the circle. The size of the sector depends on the fraction it is of the whole.

^{o}).

Example:

A group of 100 students who belonged to a school pet club were asked to name their favourite animals. The results of the survey were then displayed in a pie graph.

The graph shows that:

50% (50 students) of the 100 club members had a preference for dogs (180^{o}).

25 of the students preferred cats (90^{o}).

10 percent, or 10 students, each liked birds or guinea pigs (36^{o}).

The other 5 students chose mice as their favourite pet (18^{o}).

**Drawing a pie-chart**

**representing the popularity of various colours among people**, you need to take the following steps:

Colours |
No. of People |

Red |
4 |

Orange |
3 |

Yellow |
2 |

Green |
1 |

Colours |
No. of People |
% |

Red |
4 |
40% |

Orange |
3 |
30% |

Yellow |
2 |
20% |

Green |
1 |
10% |

**=**

*x*% x 360° (a full circle = 360°)**=**

*x*/100 x 360°**= angle**

Colours |
No. of People |
% |
Angle |

Red |
4 |
40% |
144° |

Orange |
3 |
30% |
108° |

Yellow |
2 |
20% |
72° |

Green |
1 |
10% |
36° |

**RADIUS**). This will serve as a base line to construct the pie graph.

**Label**and

**shade**the sections of the pie chart to highlight whatever data you may wish to showcase. You may also include a

**legend**if that is useful.