NO.PZ2018062016000108
问题如下：
Based on the following information the standard error of the sample mean is closest to:
选项：
A. 0.13
B. 1.19
C. 13.49
解释：
B is correct. population standard deviation is (128)^0.5=11.3137, so standard error =11.3137/{(90)^0.5}=1.19
总体标准差：(128)^0.5=11.3137,
标准误：11.3137/{(90)^0.5}=1.19
没有看懂为什么是这样
