Question

The standard deviation of 17 numbers is zero. Then

• A. the numbers are in geometric progression with common ratio not equal to one.
• B. eight numbers are positive, eight are negative and one is zero.
• C. either (a) or (b)
• D. none of these

Answer 1

The correct option is D

none of these

Standard deviation $S.D=\sqrt{Variance}$

$Variance=\frac{1}{n}{\sum }_{i=1}^n(x_i-\mu {)}^2$, where $\mu$ is the mean of the observations.

For S.D to be zero, variance should be zero. This is only possible if all the numbers are equal.