NO.PZ2017092702000139
问题如下：
For a small sample from a normally distributed population with unknown variance, the most appropriate test statistic for the mean is the:
选项：
A.z-statistic.
B.t-statistic.
C.χ2 statistic.
解释：
B is correct.
A t-statistic is the most appropriate for hypothesis tests of the population mean when the variance is unknown and the sample is small but the population is normally distributed.
对于正态分布的population，除了用known or unknown population外，还有什么方法能判断是用z还是t检验吗？