Topics
14. Data
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AustraliaNSW
Stage 3

14.09 Pie charts

Lesson
Practice
Lesson

Are you ready?

Can you identify and  compare fractions  of a circle?

Examples

Example 1

Answer the following questions.

a

Complete the statement:

A half is one whole which has been divided into ⬚ equal parts.

Worked Solution
Create a strategy

Use the table below to help:

Name of each part\text{Half}\text{Third}\text{Fourth}\text{Sixth}\text{Eighth}
Number of equal parts23468
Apply the idea

A half is one whole which has been divided into 2 equal parts.

b

Which of the following represents \dfrac{1}{2} on a circle?

A
A circle divided into 4 equal parts. One part is shaded.
B
A circle divided into 2 equal parts. One part is shaded.
Worked Solution
Create a strategy

The bottom number (denominator) tells us the number of equal parts the shape has been broken into. The top number (numerator) tells us the number of parts we have shaded.

Apply the idea

The fraction \dfrac{1}{2} is asking for 1 out of 2 parts to be shaded. So the correct answer is Option B.

Idea summary

The following table shows how many parts are in a whole:

Name of each part\text{Half}\text{Third}\text{Fourth}\text{Sixth}\text{Eight}
Number of equal parts23468

Pie charts

This video looks at the features of a pie chart including the key/legend. Understanding these key features can help us to interpret the data.

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Examples

Example 2

Every student in Year 8 was surveyed on their favourite subject, and the results are displayed in this pie chart:

This image shows a pie chart of favourite subjects. Ask your teacher for more information.
a

Which was the most popular subject?

Worked Solution
Create a strategy

Use the key to find the subject that is represented by the colour with the biggest part.

Apply the idea

We can see from the pie chart that the biggest part has the same colour as Maths in the key.

Maths was the most popular subject.

b

Which was the second most popular subject?

Worked Solution
Create a strategy

Use the key to find the subject that is represented by the colour with the second biggest part.

Apply the idea

We can see from the pie chart that the second biggest part has the same colour as History in the key.

History was the second most popular subject.

c

What percentage of the class selected Science, Phys. Ed., or Languages?

A
3\%
B
30\%
C
25\%
D
50\%
Worked Solution
Create a strategy

Find how much of the pie chart do the given subjects take up all together.

Apply the idea

The pie chart shows that the three subjects take up one quarter of the pie chart, and one quarter is equal to 25\%.

The answer is option C.

Idea summary

The key tells us what each segment of the pie chart represents. When we don't need to know exact numbers, a pie chart is a great way to see how data is spread.

Outcomes

MA3-18SP

uses appropriate methods to collect data and constructs, interprets and evaluates data displays, including dot plots, line graphs and two-way tables

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