NO.PZ2023061301000004
问题如下：
A sample mean is computed from a population with a variance of 2.45. The sample
size is 40. The standard error of the sample mean is closest to:
选项：
A.
0.039.
B.
0.247.
C.
0.387.
解释：
B is correct. Taking the square root of the known population variance to determine
the population standard deviation (σ) results in
The formula for the standard error of the sample mean (σX), based on a known
sample size (n), is
请问n是指population还是sample的size。？
