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WAEC Mathematics 2022 Paper

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Question : 42

Total: 47

The mean of two numbers x and y is 4. Find the mean of four numbers x, 2x, y and 2y

2
4
6
8

Solution:

Concept:

Use the definition of mean to first find

x + y

, then substitute this value to find the required mean.

Explanation:

The mean of

x

and

y

is

4

.

So,

\frac{x + y}{2} = 4

.

Multiply both sides by

2

:

x + y = 8

.

Now, find the mean of

x

,

2x

,

y

, and

2y

.

Mean

= \frac{x + 2x + y + 2y}{4}

.

Add the like terms:

= \frac{3x + 3y}{4}

.

Factor out

3

:

= \frac{3(x + y)}{4}

.

Substitute

x + y = 8

:

= \frac{3 \times 8}{4} = \frac{24}{4} = 6

.

Answer:

6

, which is option C.

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