a) A computer repair shop had received a number of complaints on the length of time it took to make repairs. The manager responded by increasing the repair staff by 10 percent. Complaints on repair time quickly decreased, but then complaints about the cost of repairs suddenly increased. Oddly enough, when repair costs were analyzed, the manager found that the average cost of repair had actually decreased relative to what it was before the increase in staff. What are some possible explanations for the complaints, and what actions might the manager contemplate? (b) How do you relate inspection, cost, and quality? (c) An automatic filling machine is used to fill 2-liter bottles of cola. The machine’s output is approximately normal with a mean of 2.0 liter and a standard deviation of 0.024 liters. The output is monitored using the mean of samples of 36 observations. i. Determine upper and lower control limits that will include roughly 95 percent of the sample means when the process is in control. ii. Given these sample means: 1.993, 2.007, 1.997, 2.01, 2.005, and 1.995, is the process in control?
(a) A computer repair shop had received a number of complaints on the length of time it took to make repairs. The manager responded by increasing the repair staff by 10 percent. Complaints on repair time quickly decreased, but then complaints about the cost of repairs suddenly increased. Oddly enough, when repair costs were analyzed, the manager found that the average cost of repair had actually decreased relative to what it was before the increase in staff. What are some possible explanations for the complaints, and what actions might the manager contemplate?
(b) How do you relate inspection, cost, and quality?
(c) An automatic filling machine is used to fill 2-liter bottles of cola. The machine’s output is approximately normal with a mean of 2.0 liter and a standard deviation of 0.024 liters. The output is monitored using the mean of samples of 36 observations.
i. Determine upper and lower control limits that will include roughly 95 percent of the sample means when the process is in control.
ii. Given these sample means: 1.993, 2.007, 1.997, 2.01, 2.005, and 1.995, is the process in control?
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