A random sample of size n has been selected from a normally distributed population. In hypothesis testing for the population mean, when should the t test be used instead of the z test? A) when n 30 andis unknown C) when n

Question

A random sample of size n has been selected from a normally distributed population. In hypothesis testing for the population mean, when should the t test be used instead of the z test?
A) when n < 30 andis unknown
B) when n > 30 andis unknown
C) when n < 30 andis known
D) both a and c

Quizplus · Accepted Answer

The t test should be used instead of the z test when the sample size is small (n < 30) and the population standard deviation is unknown (option a), and also when the population standard deviation is known (option c). Therefore, the correct answer is both a and c, which is option D.

A Random Sample of Size N Has Been Selected from a Normally