Each student will complete all of the following exercises and submit via the view/complete link below by midnight on Day 7.
6.3, 6.4, 6.6, 6.7, 6.8 (pp. 134-136)
Due to the text error mentioned earlier in your reading assignment section, problems 6.3 and 6.4 of this assignment are also worded differently than in your text. Please find the corrected wording for these two problems below. Note, problem 6.7 is worded correctly in your text.
6.3 The time it takes 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.
Service time, sec.
Maid Sample 1 Sample 2 Sample 3
Ann 120 90 150
Linda 130 110 140
Marie 200 180 175
Michael 165 155 140
Determine the upper and lower control limits for an X-Bar chart and an R-chart, with a sample size of four.
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?
Upon observing all four maids, it was determined that the entire group exceeded the UCL. What might explain this occurrence?
6.4 The management of the Diners Delight franchised restaurant chain is in the process of establishing quality-control charts for the time that its service people give to each customer. Management thinks the length of time that each customer is given should remain within certain limits to enhance service quality. A sample of six service people was selected, and the customer service they provided was observed four times. The activities that the service people were performing were identified, and the time to service one customer was recorded as noted below:
Service time, sec.
Determine the upper and lower control limits for an x-bar chart, and an r chart with a sample size of 6.
After the control chart was established, a sample of six service people was observed, and the following customer service times in seconds were recorded: 180, 125, 110, 98, 156, and 190. Is corrective action called for?
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