Statisticshard · Past Paper
If $x_1, x_2...x_n$ are observations such that $\sum (x_i - 2) = 20$ and $\sum (x_i - 5) = -10$, then $n$ is:
A10
B15
C20
D5
✓ Correct Answer: A — 10
$(\sum x - 2n = 20)$ and $(\sum x - 5n = -10)$. Subtracting: $3n = 30 \Rightarrow n = 10$.
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