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 the population variances are known and the population variances are unknown, but assumed to be equal

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. When the population variances are unknown or cannot be assumed equal, we use the t distribution.

When Testing the Difference Between Two Population Means Under Independent