Problem 6 for reference:

25. The McGranger Mortgage Company of Problem 6 made some changes to the process and undertook a process capability study. The following data were obtained for 15 samples of size 5 . On the basis of individual observations, management estimated the process standard deviation to be 4.21 (days) for use in the process capability analysis. The lower and upper specification limits (in days) for the mortgage process times were 5 and 25. a. Calculate the process capability index and the process capability ratio values. b. Suppose management would be happy with threesigma performance. What conclusions is management likely to draw from the capability analysis? Can valid conclusions about the process be drawn from the analysis? c. What remedial actions, if any, do you suggest that management take? 6. The McGranger Mortgage Company is interested in monitoring the performance of the mortgage process. Fifteen samples of five completed mortgage transactions each were taken during a period when the process was believed to be in control. The times to complete the transactions were measured. The means and ranges of the mortgage process transaction times, measured in days, are as follows: Subsequently, samples of size 5 were taken from the process every week for the next 10 weeks. The times were measured and the following results obtained: a. Construct the control charts for the mean and the range, using the original 15 samples. b. On the control charts developed in part (a), plot the values from samples 16 through 25 and comment on whether the process is in control