Question

A sample of 144 was taken from a population with a standard deviation of 36 inches. In this case, the sample mean will be within how many inches of the population mean 99.7% of the time?

A. 9
B. 6
C. 3
D. 12

Answer 1

Stats was never my strong subject however I believe the answer is
\[\sigma_{x}=\frac{ \sigma }{ \sqrt{n} }\]

so you know n which is the sample size, and you know sigma which is the standard deviation

Answer 2

but I think since 99.7% is equal to three standard deviations, you have to multiply your answer by 3
@Nnesha