4. Because of high production-changeover time and costs, a director of manufacturing must convince management that a proposed manufacturing method reduces costs before the new method can be implemented. The current production method operates with a mean cost of $220 per hour. A research study will measure the cost of the new method over a sample production period.

a. Develop the null and alternative hypotheses most appropriate for this study.

b. Comment on the conclusion when H0 cannot be rejected.

c. Comment on the conclusion when H0 can be rejected.