老师 翻一下这个题目

问题如下：

For simple random samples of size n from a population with a mean and a variance but without knowing distribution, the sampling distribution of the sample mean approaches normal distribution if the sample size is :

选项：

small

large

irrelevant

解释：

B is correct. Because when sample size is sufficiently large(n≥30), sampling distribution is approximately equal to the population mean.

因为当样本量足够大（n≥30）时，抽样分布趋近于正态分布，所以样本均值趋近于总体均值。