JAMB 2002 · UME · Q26

Statistics: data & averages

Find the mean of the data 7, −3, 4, −2, 5, −9, 4, 8, −6, 12.

Worked solution (try it first)

Add the positives: $7 + 4 + 5 + 4 + 8 + 12 = 40$ .
Add the negatives: $-3 - 2 - 9 - 6 = -20$ .
So the total is $40 - 20 = 20$ .
There are 10 values, so the mean is $\frac{20}{10} = 2$ , option B.

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