Fowle Marketing research, inc., bases charges to a client on the assumption that telephone surveys can be completed within 15 minutes or less. If more time is required, a premium rate is charged with a sample of 35 surveys, a population standard deviation of 4 minutes, and a level of significance of .01, the sample mean will be used to test the null hypothesis H0: µ ≤ 15.

a. What is your interpretation of the type II error for this problem? What is its impact on the firm?

b. What is the probability of making a type II error when the actual mean time is µ = 17 minutes?

c. What is the probability of making a type II error when the actual mean time is µ = 18 minutes?