When is a t-test used instead of a z-test?
A)When the population µ is known
B)When the population deals with two samples
C)When the population standard deviation is known
D)When the population standard deviation is unknown

Question

Quizplus · Accepted Answer

A t-test should be used when the population standard deviation is unknown and the sample size is small (typically less than 30). A z-test is used when the population standard deviation is known or when the sample size is sufficiently large (typically greater than 30). Therefore, in this case, the best choice is D.

When Is a T-Test Used Instead of a Z-Test