JAMB 1984 · UME · Q7

Statistics: data & averages

Thirty boys and $x$ girls sat for a test. The mean scores of the boys and of the girls were 6 and 8 respectively. Find $x$ if the total score was 468.

Worked solution (try it first)

Total score = mean × number.
The boys scored $30 \times 6 = 180$ and the girls $8x$ .
So $180 + 8x = 468$ , which gives $8x = 288$ .
Divide by 8: $x = 36$ , option C.

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