Numeracy Worksheet - Castlebrae Community High School - 2012 Page 33
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47FHS Numeracy
contents page
Ratio
A ratio allows us to compare amounts.
When writing a ratio we usually use “ : ”,
1 : 3
When reading a ratio we use the word “to”, 1 to 3
The order of the numbers in a ratio matters,
1 : 3 is NOT the same as 3 : 1
Example 1
The ratio of beads is
:
:
Level 3
3 : 4
4 : 3
3 to 4
4 to 3
When quantities are to be mixed together, the ratio, or proportion
of each quantity is often given. The ratio can be used to calculate
the amount of each quantity.
Example 2
To make a fruit drink, 4 parts water is mixed with 1 part of cordial.
Level 3
The ratio of
water to cordial is
4 : 1
The ratio of
cordial to water is
1 : 4
Example 3 In a bag of balloons, there are 5 pink, 7 blue and 8 yellow balloons.
Level 3
The ratio of
pink : blue : yellow is
5 : 7 : 8
Simplifying Ratios
Ratios which describe the same proportion are known as equivalent ratios.
Ratios can be simplified in much the same way as fractions.
Example 4 Purple paint can be made by mixing 10 tins of blue paint with 6 tins of
Level 3
red. The ratio of blue to red can be written as 10 : 6
:
B B B B B
R R R
Blue : Red
10 : 6
B B B B B
R R R
÷ 2
÷ 2
:
5 : 3
B B B B B
R R R
33
L Watson 2012
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