A Manager of the Credit Department for an Oil Company

Multiple Choice

A manager of the credit department for an oil company would like to determine whether the average 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) t test of a population proportion.
B) Z test of a population proportion.
C) Z test of a population mean.
D) t test of a population mean.