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 selected. 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
Question 2
The life expectancy of a particular brand of tire is normally distributed with a mean of 40,000 and a standard deviation of 5,000 miles. What percentage of tires will have a life of 34,000 to 46,000 miles?
a. 38.49
b. 76.98
c. 50
d. None of the answers is correct.