The stated goal of a chain of service stores is to provide a lube and oil change

Question

The stated goal of a chain of service stores is to provide a lube and oil change for anyone's automobile in 15 minutes. The manager at one store thinks that there is a growing disparity among his workers in the time it takes to lube and change the oil of an automobile. To monitor this, the manager has selected a sample of 20 days and has recorded the time it took five randomly selected employees to service an automobile. The data are found below. Complete parts a through d Click the icon to view the data. a. The manager noticed that the longest time it took to service a car was 25.48 minutes. Suppose the distribution of times to service a car was normal, with a mean of 15. Use your knowledge of a normal distribution to let the manager know what the standard deviation is for the time it takes to service a car The standard deviation is ? minutes. Round to two decimal places as needed.) b. Use the data to construct an x- and an R-chart Construct a control chart for the range. Which graph below shows an R-chart for the data? A. O B. ? ?. 0 10 20 10 20 10 20 Construct a control chart for the mean. Which graph below shows an x-chart for the data? O A. ??. O C. 10 0 10 20 0 10 20 10 c. Based on these data, what would you conclude about the service process? A. Since ten points in a row are below the centerline on the R-chart, the process is out of control. O B. C. D. Since one point on the x-chart is below the lower control limit, the process is out of control. Since one point on the R-chart is above the upper control limit, the process is out of control. Since all of the points on the R-chart and x-chart are between the control limits, the process is under control. Click to select your answer(s).

Explanation / Answer

Answer

Part (a)

Standard deviation is 2.7112 Minutes

Part (b)

i) Option C

ii) Option A

Part (C)

Option (c)

i.e since one point on R chart is above upper control limit ,the process is out of control.

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