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 fol-lowing times in seconds: 185, 150, 192, and 178. Is corrective action needed?

Transcribed Image Text:

Service Time, Sec. Maid Ann Linda Marie Michael Sample 1 120 130 200 165 Sample 2 90 110 180 155 Sample 3 150 140 175 140