Chapter 2.4, Problem 2.70ACA

Estimating production time. A widely used technique for estimating the length of time it takes workers to produce a product is the time study. In a time study, the task to be studied is divided into measurable parts, and each is timed with a stopwatch or filmed for later analysis. For each worker, this process is repeated many times for each subtask. Then the average and standard deviation of the time required to complete each subtask are computed for each worker. A worker’s overall time to complete the task under study is then determined by adding his or her subtask-time averages (Gaither and Frazier, Operations Management, 2001). The data (in minutes) given in the table are the result of a time study of a production operation involving two subtasks.

1. a. Find the overall time it took each worker to complete the manufacturing operation under study.
2. b. For each worker, find the standard deviation of the seven times for subtask 1.
3. c. In the context of this problem, what are the standard deviations you computed in part b measuring?
4. d. Repeat part b for subtask 2.
5. e. If you could choose workers similar to A or workers similar to B to perform subtasks 1 and 2, which type would you assign to each subtask? Explain your decisions on the basis of your answers to parts a–d.