问题
单项选择题
From a population of 5000 observations, a sample of n=100 is selected. Calculate the standard error of the sample mean if the population standard deviation is 50.（）
A. 4.48.
B. 5.00.
C. 4.00.
答案
参考答案：B
解析：
The standard error of the sample mean equals the standard deviation of the population divided by the square root of the sample size: 50/(100)1/2=5.