pooled estimator在什么情况下应用呢？

同学你好，

关于pooled estimator ，原版书有一道题，这道题目选择B。掌握这个即可，这是特定假设检验下应用的特定概念，不是很重要。

A pooled estimator is used when testing a hypothesis concerning the:
A equality of the variances of two normally distributed populations.
B difference between the means of two at least approximately normally distributed populations with unknown but assumed equal variances.
C difference between the means of two at least approximately normally distributed populations with unknown and assumed unequal variances