Consider the data in Exercise 812 Follow the instructions be

Consider the data in Exercise 8-12. Follow the instructions below. Using all the data, compute trial control limits for individuals-moving-range (X/MR) charts. Draw the X/MR charts. Identify any samples that are out of control. Note that m = 20, summation x_i = 1069, summation mr_i = 70. R commands are given below. If you do part (a) correctly, then you should conclude that the moving range value mr_9 = 13 is out of control. This means that either x-8 = 62 or x_9 = 49 is an unusual observation. Notice that x_8 = 62 is very large compared to the rest of the values (it clearly sticks out on the X chart). Thus, in revising the control limits, 62 should be removed from the data. The revised X/MR charts are given below. Now, both charts indicate that the process is stable. Estimate the process mean and standard deviation for the stable process. Exclude the x_8 = 62 from the calculations. For recalculating mr, note that you will delete original mr_8 = 8 and mr_9 = 13 and replace them with mr_9 = |49 - 54| = 5. Hence, summation mr_i = 70 - 8 - 13 + 5 = 54 which is summed over 18 moving ranges. Twenty samples of size 4 are drawn from a process at 1-hour intervals, and the following data are obtained: summation i = 1 20 x_i = 378.50 summation i = 1 20 r_i = 7.80 Find trial control limits for X and R charts. Assuming that the process is in control, estimate the process mean and standard deviation.

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