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BECE Mathematics 2017 Paper

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Question : 2

Total: 40

If

21: 2x = 7: 12

, find the value of

x

10
12
15
18

Solution:

Concept:

A ratio can be written as a fraction, and the unknown can be found by cross multiplication.

Explanation:

Write the given proportion as

\frac{21}{2x} = \frac{7}{12}

.

Cross multiply to get

21 \times 12 = 7 \times 2x

.

This simplifies to

252 = 14x

.

Divide both sides by

14

:

x = \frac{252}{14} = 18

.

Thus,

x = 18

satisfies the given ratio.

Answer:

x = 18

(Option D)

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