Q 27

In developing an interval estimate of the population mean, if the population standard deviation is unknown
A)it is impossible to develop an interval estimate
B)a sample proportion can be used
C)the sample standard deviation and t distribution can be used
D)None of the other answers are correct.

Q 28

A bank manager wishes to estimate the average waiting time for customers in line for tellers. A random sample of 50 times is measured and the average waiting time is 5.7 minutes. The population standard deviation of waiting time is 2 minutes. Which Excel function would be used to construct a confidence interval estimate?
A)CONFIDENCE.NORM
B)NORM.INV
C)T.INV
D)INT

Q 29

An auto manufacturer wants to estimate the annual income of owners of a particular model of automobile. A random sample of 200 current owners is taken. The population standard deviation is known. Which Excel function would not be appropriate to use to construct a confidence interval estimate?
A)NORM.S.INV
B)COUNTIF
C)AVERAGE
D)STDEV.S