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WAEC Mathematics 2014 Paper

Question : 21

Total: 49

If x : y = 3 : 2 and y : z = 5 : 4, find the value of x in the ratio x : y : z

Solution:

Concept:

Make the common term

y

equal in both ratios using the least common multiple (LCM).

Explanation:

The ratios are

x : y = 3 : 2

and

y : z = 5 : 4

The

y

-terms are

2

and

5

. Their LCM is

10

Convert each ratio so that

y = 10

x : y = 3 : 2 = 15 : 10

y : z = 5 : 4 = 10 : 8

Now combine them as

x : y : z = 15 : 10 : 8

Answer:

In the ratio

x : y : z

x = 15

The correct option is C.

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