Ratio
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Transcript of Ratio
April 12, 2023
Ratio
1. Using ratios
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April 12, 2023
When a quantity is divided into parts the ratio compares the amounts.
Here the parts are equal, so the ratio is 1:1
1 1:
Explanation
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April 12, 2023
When a quantity is divided into parts the ratio compares the amounts.
Here the parts are equal, so the ratio is 1:1
1 1:
A quantity may be divided into more than two parts.
Explanation
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April 12, 2023
When a quantity is divided into parts the ratio compares the amounts.
A quantity may be divided into more than two parts.
3 : 2 : 1
When you multiply or divide the numbers in a ratio by the same number, you get an equivalent ratio.
6 4 2
× 2
Explanation
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April 12, 2023
When a quantity is divided into parts the ratio compares the amounts.
A quantity may be divided into more than two parts.
When you multiply or divide the numbers in a ratio by the same number, you get an equivalent ratio.
: :6 4 2
The ratio 6:4:2 can be simplified to 3:2:1
3 2 1
Explanation
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April 12, 2023
Complete this table of equivalent ratios.
2:63:94:125:15
4:66:98:12
10:15
4:146:218:28
10:35
2:72:31:3× 2× 3× 4× 5
Fill in the equivalent ratios in these sequences.
1:2 2:4 4:82:3 6:9 8:12
2:10 3:153:4 6:8
3:64:6
1:5 4:209:12 12:16
Practise
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April 12, 2023
Two families visit the cinema on a day when all adults pay the child price.There are five Pattersons and three Khans. The bill comes to £20. How much should each family pay?
Total the numbers in the ratio.
5:3Work out the ratio of Pattersons to Khans.
8
£2.50
£12.50 £7.50Multiply your answer by each number in the original ratio.
Divide the total cost by this number.
×3×5
The Pattersons pay £12.50 and the Khans £7.50.
Example
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April 12, 2023
Two brothers, Jake and Dino run an office cleaning company. They have decided to split the profits according to how many days each works in a week.Jake works Mondays and Thursdays and Dino works Tuesdays, Wednesdays and Fridays.
In one week they make £1,900. How much should each brother get?
They work 5 days in total1900
5= 380
Jake receives 2 × £380
and Dino receives 3 × £380
So
=
=
£760
£1140
Example
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April 12, 2023
1:3
The ratio of boys to girls who study ballet in the UK is
1:3 In a town, 45 girls are learning ballet.
How many boys would you expect to also be learning?
45
To make 45 from 3, you need to use the multiplier 15.
×15
To keep the ratio equivalent, you also need to multiply the 1 by 15.
×1515:
You would expect 15 boys to be studying ballet.
boys girls
Example
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April 12, 2023
A multiplier may not always be obvious. To find it you may need to use division.To make enough orange paint to cover a room, you need to mix 2 parts yellow to every 5 parts red.How much yellow paint will you need to mix with 7 litres of red paint?
2:5
To find the multiplier divide the 7 litres of red paint by the 5 in the ratio. = 1.47 ÷ 5
yellow red
×1.4
7×1.4
2.8:
You need 2.8 litres of yellow paint.
Example
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