year 8 maths

5A
Introducing ratios
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5A Introducing ratios
So far you have used fractions, decimals and percentages to describe situations like the seating plan in
this diagram.
G G G B B
G G G B B
G G G B B
G G G B B
The seating plan for my class
(G is 1 girl and B is 1 boy.)
In this chapter you will learn how to use ratio to compare two or more quantities.
The simplest ratio is 1 is to 1 .
In this diagram the ratio of red squares to green squares is 1 : 1 .
This is pronounced ‘ 1 is to 1 ’.
Half of the squares are red and half are green .
In this diagram, the ratio of red squares to green squares is 2 : 1 .
Two-thirds are red and one-third is green .
In this diagram, the ratio of red squares to green squares is 1 : 2 .
One-third is red and two-thirds are green .
Let’s start: Seating plan
Consider the seating plan at the top of the page.
• What fraction of the class are girls?
• What fraction of the class are boys?
• What is the ratio of girls to boys?
• What is the ratio of boys to girls?
Cambridge Maths NSW
Stage 4 Year 8 Second edition
ISBN 978-1-108-46627-1 © Palmer et al. 2018
Cambridge University Press
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