A sample of 20 items from a population with an unknown $\sigma$ is selected in order to develop an interval estimate of $\mu$. Which of the following is not necessary?
A)We must assume the population has a normal distribution.
B)We must use a t distribution.
C)Sample standard deviation must be used to estimate $\sigma$.
D)The sample must have a normal distribution.

Question

Quizplus · Accepted Answer

The sample does not need to have a normal distribution in order to use a t distribution for interval estimation of the population mean. However, the other options are necessary. We do need to assume that the population has a normal distribution, use a t distribution for small sample sizes, and estimate the population standard deviation using the sample standard deviation.

A Sample of 20 Items from a Population with an Unknown