NECO 2024 · Paper 2 · Q4

1. First the mean: $2 + 6 + 9 + 8 + 7 + 9 + 8 + 7 = 56$, and there are 8 numbers, so $\bar x = \frac{56}{8} = 7$.

(i)

1. The distances from 7, ignoring signs, are $|x - 7| = 5, 1, 2, 1, 0, 2, 1, 0$, which add up to 12.
2. Mean deviation $= \frac{12}{8} = 1.50$.

(ii)

1. Square each deviation: $(x - 7)^2 = 25, 1, 4, 1, 0, 4, 1, 0$, which add up to 36.
2. Variance $= \frac{36}{8} = 4.5$, so the standard deviation is $\sqrt{4.5} \approx 2.12$.