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 youuse?

A. Z-test of a population mean

B. Z-test of a population proportion

C. t-test of a population proportion

D. t-test of population mean

Ques (9)