Question

# The sum of n observations is 100 and the sum of squares of these n observations is 500. Then which of the following is a possible value of n?

A
17
B
19
C
21
D
18

Solution

## The correct option is C 21The variance is always non-negative. σ2≥0⇒∑x2n−(¯¯¯x)2≥0⇒500n−(100n)2≥0⇒500n−10000≥0⇒n≥20

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