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JAMB Mathematics 2022 Paper

Question : 33

Total: 39

If y varies inversely as x and x = 3 when y =4. Find the value of x when y = 12

Solution:

Concept:

Inverse variation means as one quantity increases, the other decreases. Their product is constant.

Explanation:

Since

y

varies inversely as

x

, write

y = \frac{k}{x}

, where

k

is the constant of variation.

Substitute

x = 3

and

y = 4

into

y = \frac{k}{x}

4 = \frac{k}{3}

Multiply both sides by

3

k = 12

Alternatively, use

k = xy = 3 \times 4 = 12

Now find

x

when

y = 12

Use

x = \frac{k}{y}

Therefore,

x = \frac{12}{12} = 1

Answer:

The value of

x

1

, which is option B.

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