Albert Teen
Probability & Statistics

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Pie Charts

Pie Charts

Pie Charts

Pie charts are a great visual way to display the relative proportions of quantitative data.

Pie charts are a nice visual way to display information about qualitative or discrete quantitative data, where the size of each part is proportional to the quantity it represents.

1

Let's imagine we ask 60 people about their favourite type of takeaway.

Each of the categories (types of takeaway) will occupy a single slice of the pie chart, where the size of the slice will be proportional to the frequency of people who picked each type of takeaway.

2

What do the angles in a circle add up to?

3

The angles in a circle add up to $360 \degree$

Therefore, we can calculate the size of each section using the formula: $\dfrac{frequency}{total \space frequency} \times 360$

4

The sector angle for Chinese is $78\degree$

Chinese represents 13 of the total frequency of 60. Therefore, using the formula: $\dfrac{13}{60} \times 360=78\degree$

5

What is the sector angle for Indian?

6

The sector angle for Indian is $84\degree$

$\dfrac{14}{60} \times 360=84$

7

What is the sector angle for Fish and Chips?

8

The sector angle for Fish and Chips is $78\degree$

$\dfrac{8}{60} \times 360=48$

9

We can put these values into a pie chart

The angle of the sector from the centre controls the size. Therefore, since Pizza is the most popular choice, it has the largest slice of the pie.