QSR routinely examines fast-food drive-through service times. Recent research by the magazine indicates that the mean time a car spends in a McDonald’s drive-through is 167.1 seconds. A McDonald’s manager in Salt Lake City feels that she has instituted a drive-through policy that results in lower drive-through service times. A random sample of 70 cars results in a mean service time of 163.9 seconds with standard deviation 15.3 seconds. Determine whether the policy is effective in reducing drive-through service times.

(a) State the null and alternative hypotheses.

(b) Because the cost of instituting the policy is quite high, the quality-control researcher at McDonald’s chooses to test the hypothesis using an α = 0.01 level of significance. Why is this a good idea?

(c) Conduct the appropriate test to determine if the policy is effective.