Quadradinho · 2019年11月11日
问题如下：
A population has a mean of 25 but its standard deviation is unknown. we select 100 members from the population to form a sample with a mean of 22.5 and a variance of 16. Calculate the standard error of the sample mean :
选项：
A.0.04.
B.0.2.
C.0.40.
解释：
C is correct.
请问这题求的是什么？ 看不懂怎么计算的。
NO.PZ2015120604000116问题如下 A population ha meof 25 but its stanrviation is unknown. we sele 100 members from the population to form a sample with a meof 22.5 ana varianof 16. Calculate the stanrerror of the sample me:A.0.04.B.0.2.C.0.40.C is correct.sX¯=sn=4100=410=0.4根据中心极限定理，样本均值是等于总体均值，题干中为何不相等？
NO.PZ2015120604000116 请问老师课堂上讲了stanrrror涉及到了两个公式，有一个直接用样本的均值减去总体的均值，这里可以直接这样代入吗，什么时候用相减的那个公式。
