The service manager for an automotive repair corporation wants to study the length of time required to replace the rear drum brakes of automobiles. A subgroup of 10 automobiles needing their brakes replaced was selected on each day for a period of 20 days. The accompanying data show the subgroup repair times. Complete parts a through c below. Click the icon to view the brake repair data. a. The manager has been trying to get the average time required to replace the rear drum brakes for subgroups of 10 automobiles to be under 2.5 hours. Use the data to determine if he has reached his goal. Use a = 0.10. What are the null and alternative hypotheses? A. H: 122.5 HA: 2.5 evidence that the average time required to replace the rear drum brakes of an automobile is 2.5 hours. b. Set up the appropriate control charts to determine if this process is under control. Construct an x-chart. Choose the correct graph below. A. Q B. 10 12 14 16 18 20 Auto Sample Q O D. C. 6 8 10 12 14 16 18 20 AutoSample 10 12 14 16 18 20 AutoSample Q 10 12 14 16 18 20 Sample Account