A sample of 20 items from a population with an unknown σ is selected in order to develop an interval estimate of μ. 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 σ.
D) The sample must have a normal distribution.

Question

Quizplus · Accepted Answer

The sample itself does not need to have a normal distribution; however, the population from which the sample is drawn should be approximately normal, especially for small sample sizes, to justify using the t-distribution.

A Sample of 20 Items from a Population with an Unknown