An appliance manufacturer is considering the purchase of a new machine for stamping out sheet metal parts. If μ0 (given) is the true average of the number of good parts stamped out per hour by their old machine and μ is the corresponding true unknown average for the new machine, the manufacturer wants to test the null hypothesis μ = μ0 versus a suitable alternative. What should the alternative be if he does not want to buy the new machine unless it is
(a) More productive than the old one?
(b) At least 20% more productive than the old one?