21. (6 points) Consider the following four-step assembly operation with quality problems. All resources are staffed by one employee. a. The first resource has a processing time of 5 minutes per unit. b. The second resource has a processing time of 6 minutes per unit. c. The third resource has a processing time of 3 minutes per unit. With a 30% probability, the flow unit coming out of the third resource has to be reworked. In that case, the operations at the first, second, and third resources are repeated. You can assume that (a) rework always succeeds (i.e., a unit going through the rework loop will always work after the third resource) and (b) the processing times for units in rework are the same as for regular units. d. The fourth resource has a processing time of 4 minutes per unit. What is the capacity of the process (in units per hour)? What is the capacity of the process (in units per hour)? Answer: 17 units per hour Good Rework Total per unit IU per minute WU Resource 1 Resource 2 Resource 3 Resource 4 0.7 x 5 0.7 X6 0.7 X 3 1.00 X 4 0.3 * 5+5 0.3 x 16 + 61 0.3 M 13 + 3 3.5+ 36.5 4.2 + 3.6 7.8 2.1 + 1.8 3.0 4 6.5/1 6.5 7.8/17.8 3.9/1 3.9 4/1