WAEC 2024 · Paper 1 · Q40

Dispersion & cumulative frequency

The masses (in kg) of members in a club are 59, 44, 53, 57, 49, 40, 48 and 50. Calculate the variance of the distribution.

Worked solution (try it first)

The masses add up to 400 and there are 8 of them, so the mean is 50 kg.
The deviations are 9, $-6$ , 3, 7, $-1$ , $-10$ , $-2$ , 0.
Their squares add up to $81 + 36 + 9 + 49 + 1 + 100 + 4 + 0 = 280$ .
The variance is $\frac{280}{8} = 35$ , option A.

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