Question

Find the standard deviation for the given data. Round your answer to one more decimal place than the original data.

15, 42, 53, 7, 9, 12, 14, 28, 47
A. 29.1

B. 16.6

C. 17.8

D. 15.8

is it C

Answer 1

First find the mean, μ where
μ = (sum of all numbers, Σxi)/(number of values, N)

Standard deviation, σ, is given by
σ²=(sum of (xi-μ)²)/N
and finally
σ=sqrt(σ²)

Answer 2

C is not correct. There is a choice which is close to the answer.

The previous post shows how you can find the correct answer.

Answer 3

Correction:
The equation given above
σ²=(sum of (xi-μ)²)/N
applies to a population.

C is correct if we interpret the data as a sample of the given population, in which case the standard deviation is given as:
σ²=(sum of (xi-μ)²)/(N-1)
= 17.8