When testing the difference between two population means under independent sampling,we use the z distribution if ____________.
A)The population variances are known
B)The population variances are unknown,but assumed to be equal
C)The population variances are unknown and cannot be assumed equal
D)Both A and B

Question

Quizplus · Accepted Answer

When testing the difference between two population means under independent sampling, we use the z distribution if the population variances are known. This is because we can use the pooled variance estimate to calculate the standard error of the difference between the sample means. However, if the population variances are unknown, we need to use the t distribution instead.

When Testing the Difference Between Two Population Means Under Independent