Cambridge International Mathematics

14 Assumed Knowledge (Number)

Example 19 Self Tutor

Write as a ratio, without simplifying your answer:

a Jack has$5and Jill has 50 cents.

b Mix 200 ml of cordial with 1 litre of water.

a Jack : Jill=$5:50cents

= 500cents:50cents

= 500 : 50

fwrite in the correct orderg

fwrite in the same unitsg

fexpress without unitsg

b cordial : water= 200ml:1litre

= 200ml: 1000ml

= 200 : 1000

fwrite in the correct orderg

fwrite in the same unitsg

fexpress without unitsg

1aFind the ratio of squares to triangles in:

b Find the ratio of|stoÄs in:

c Find the ratio of:

i signs to signs

ii signs to signs

iii s to signs

iv signs to s.

2 Write as a ratio, without simplifying your answer:

a $8is to$3 b 3 litres is to 7 litres c 35 kg is to 45 kg

d $ 3 is to 50 pence e 500 ml is to 3 litres f 400 misto 2 : 5 km

g 9 km is to 150 m h 12 misto 8 km i 4 histo 40 min

SIMPLIFYING RATIOS

If we have 6 apples and 4 bananas, we have 3 apples for every 2 bananas.

So, 6:4is the same as 3:2.

We say that 6:4and 3:2areequal ratios.

Notice that to get from6:4to3:2we can divide each number in the first ratio by 2.

Also, to get from 3:2to 6:4we can multiply each number in the first ratio by 2.

Tosimplify a ratiowe can multiply or divide each part by the same non-zero number.

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EXERCISE F.1

IGCSE01

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