RATIO

• Mathematics
• Upper Secondary (Key Stage 4)
• GCSE

RATIO

What do you think a ratio is?

A ratio is simply a comparison of 2 or more similar quantities

A ratio is simply a comparison of 2 or more similar quantities.

We use a colon :  to separate the numbers

In a Smarties pack, if there are 20 pink, 25 blue and 30 yellow Smarties, then the ratio of pink to blue to yellow is 20:25:30

The order is really important!

Can you think of any other ratios in everyday life?

There are 24 men and 8 women in an office. What is the ratio of women to men?

Can we simplify our answer?

The ratio for diluting juice is 1 part juice to 8 parts water. How much water would I need for 200ml of juice?

A recipe uses a ratio of 4 parts flour to 2 parts sugar to 1 part margarine. How much sugar and margarine would I need for 800g of flour?

In a class there are 10 girls and 8 boys. What is the ratio of boys to girls in its simplified form?

1. 10:8
2. 8:10
3. 4:5
4. 5:4

A paint mixture uses 3 parts blue paint to 8 parts red paint. How much red paint would I need for 600ml of blue paint?

1. 1000ml
2. 800ml
3. 2400ml
4. 1600ml

A builder makes concrete using a ratio of 3 parts cement, 2 parts sand, 1 part water. How much sand would he need with 12kg of cement?

1. 6kg
2. 10kg
3. 8kg
4. 12kg

Dividing a quantity into a given ratio

You and your 3 friends have been running a lottery syndicate. You decide to share any winnings in the ratio 1:2:3:4 as some people have put more money in than others. 

You win £10,000. How much does each person get?

Step 1:   Add your parts together.

Step 2:  Divide the amount by your parts to get the value of 1 part.

Step 3:  Multiply this back into the ratio

3 boys share £60 in the ratio 2 : 4 : 6

How much does each boy get?

The ratio of iphones to android phones sold in the UK is 3:1. If there are 16 million phones sold each year, How many iphones are sold?

1. 10 million
2. 12 million
3. 8 million
4. 4 million

Jack drinks a bottle of diluted juice. The bottle is 500ml. If the ratio of juice to water is 1 : 4 how much water is in his bottle?

1. 400ml
2. 100ml
3. 200ml
4. 300ml

How do you feel about ratios after our lesson?

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