Service Management 7th Edition by James Fitzsimmons, Mona Fitzsimmons

Exercise 7

The time to make beds at a motel should fall into an agreed-on range of times. A sample of four maids was selected, and the time needed to make a bed was observed on three different occasions:

a. Determine the upper and lower control limits for an X -chart and an R -chart with a sample size of four.
b. After the control chart was established, a sample of four observations had the following times in seconds: 185, 150, 192, and 178. Is corrective action needed?