NO.PZ2016062402000019
问题如下:
A population has a known mean of 1,000. Suppose 1,600 samples are randomly drawn (with replacement) from this population. The mean of the observed samples is 998.7, and the standard deviation of the observed samples is 100. What is the standard error of the sample mean?
选项:
A.0.025
B.0.25
C.2.5
D.25
解释:
This is , or = = 2.5. Other numbers are irrelevant.
每次随机抽取1600个样本,每次抽取都有一个均值, 所有均值 的 均值就是998.7对吧?然后这个standard deviation of the observed sample是指什么?还是说998.7和100只是其中一次抽取的均值和sd?