你好

问题如下：

Assume that the variance is unknown, which of the following statements on a hypothesis tests of the population mean is most accurate?

选项：

A.

If the sample is small, it's a t-test.

B.

If the sample is large, it's a t-test.

C.

If the sample is small, it's a z-test.

解释：

B is correct. If the population sampled has unknown variance, the sample is large, or the sample is small but the population sampled is normally distrubuted, or approximately normally distributed, then the test statistic for hypothesis tests concerning a single population mean.