A manager of the credit department for an oil company would like to determine whether the mean monthly balance of credit card holders is equal to $75.An auditor selects a random sample of 100 accounts and finds that the mean owed is $83.40 with a sample standard deviation of $23.65.If you were to conduct a test to determine whether the auditor should conclude that there is evidence that the mean balance is different from $75,which test would you use?
A)Z-test of a population mean
B)Z-test of a population proportion
C)t-test of population mean
D)t-test of a population proportion

Question

Quizplus · Accepted Answer

Since the population standard deviation is not known and the sample size is below 30, a t-test should be used to determine if there is evidence that the mean balance is different from the assumed population mean of $75.

A Manager of the Credit Department for an Oil Company