Suppose that we know that the sample mean is 18 and the population standard deviation is 3. We want to test the null hypothesis that the population mean is 20. In this situation we would
A) reject the null hypothesis at a = .05.
B) reject the null hypothesis at a = .01
C) retain the null hypothesis.
D) We cannot solve this problem without knowing the sample size.

Question

Quizplus · Accepted Answer

The sample size is crucial for determining the standard error of the mean, which is needed to calculate the test statistic for hypothesis testing. Without the sample size, we cannot determine the likelihood of observing a sample mean of 18 if the population mean is truly 20, and thus cannot decide whether to reject or retain the null hypothesis.

Suppose That We Know That the Sample Mean Is 18