Question

The Money Pit 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:

                                                                                                                                                

Sample	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
Mean	19	16	10	19	14	16	17	18	15	16	17	11	13	11	14
Range	4	10	3	7	8	12	11	14	9	9	10	5	8	10	12

​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:

                                                                                                      

Sample	16	17	18	19	20	21	22	23	24	25
Mean	13	16	11	17	19	22	15	24	22	20
Range	5	10	5	3	11	14	10	9	7	5

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Click the icon to view the table of factors for calculating​ three-sigma limits for the

x overbarx​-chart

and​ R-chart.

a. Construct the control charts for the mean and the​ range, using the original 15 samples.

Set up the​ R-chart by specifying the center line and​ three-sigma control limits below. ​(Enter your responses rounded to two decimal​ places.)

Answer 1