Car repair shop data.

Problem 1, p. 409
Make a check sheet and then a Pareto diagram for the following car repair shop data.

Problem, 4, page 410
Prepare a run diagram for this emergency call data. Use five-minute intervals (i.e., count the calls received in each five-minute interval. Use intervals of 0 to 4, 5 to 9, etc.). Note: Two or more calls may occur in the same minute; there were three operators on duty this night. What can you conclude from the run chart?

Stevenson, William J; Stevenson, William J. Operations Management (Page 410). McGraw-Hill Higher Education. Kindle Edition.

Problem 7, page 455

The postmaster of a small western town receives a certain number of complaints each day about mail delivery. Determine three-sigma control limits using the following data. Is the process in control?

Problem 13 page 456

For each of the accompanying control charts, analyze the data using both median and up/down run tests with z = ± 1.96 limits. Are nonrandom variations present? Assume the center line is the longterm median.

Sample Solution