Questions on this topic are targeted at the grades indicated.

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18

UNIT 1

DCBAA

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RatioRatios are often used in real-life situations such as cooking.

Jared is preparing the ingredients for a pizza.

He uses cheese, topping and dough in the ratio 2 : 3 : 5.He uses 70 grams of dough.

How many grams of topping will Jared use?

cheese : topping : dough 2 : 3 : 5 ? : ? : 70 g70

__ 5 143 14 42 g of topping

Ratios are used to compare quantities.You can fi nd EQUIVALENT RATIOS by

multiplying or dividing by the same number.

A ratio can be written as a fraction.In a drama group, if the ratio of boys to girls is 2 : 5, then 2 __ 7 of the group are boys and 5 __ 7 are girls.

5 : 9

10 : 18

1 : 1.8

�2�2

�10 �10

This equivalent ratio is in the form 1 : n.This is useful for calculations.

You can use ratios to work out which of these jars of honey is better VALUE FOR MONEY.

STANDARD

450 g£2.70

HONEY

SUPER

580 g£3.19

HONEY450 : 270

1 : 0.6

�450�450

580 : 319

1 : 0.55

�580�580

The cost per gram is 0.6 p.

The cost per gram is 0.55 p.

The SUPER jar is better value for money because it costs less per gram.

Three women won a total of £360.They shared the money in the ratio 7 : 3 : 2.Donna received the largest amount.Work out the amount Donna received.

7 3 2 12

360 _____ 12 £30

£30 7 £210Donna received £210.

1. Work out the total number of parts.2. Work out the value of 1 part.3. Work out 7 parts (largest part) for

Donna.

They shared the money in the ratio 7 : 3 : 2.

grade

C

Tom is making plum crumble.For the crumble topping, he uses sugar, butter and fl our in the ratio 2 : 3 : 5.Tom uses 250 g of plums for every 400 g of crumble topping.

grade

CTom has 0.5 kg of plums. He uses all of them.Work out how much sugar, butter and fl our he will need for the crumble topping. (4 marks)

You fi rst need to convert 0.5 kg into grams.Then work out how much crumble topping Tom needs to make.

Draft