The National Assessment of Educational Progress (NAEP) includes a mathematics test
for eighth-graders. Scores on the test range from 0 to 500. Suppose that you give the NAEP test to an SRS of961eighth-graders from a large population in which the scores have mean μ = 281 and standard deviation σ = 123. The mean x will vary if you take repeated samples.
The sampling distribution of x is approximately Normal. It has mean μ = 281. What is its standard deviation? round to three decimal places