Twenty-five samples of size n = 5 were collected to construct an
-chart. The accompanying sample means and ranges were calculated for these data.
![](https://test.transtutors.com/qimg/9eb407b9-9bdb-4873-9a0f-88f326a1cf5c.png)
a. Calculate the mean of the sample means,
and the mean of the sample ranges, ![](https://test.transtutors.com/qimg/b557a7e6-aaab-4333-96d1-e7a9a4e8118d.png)
b. Calculate and plot the centerline and the upper and lower control limits for the
-chart..
c. Calculate and plot the A, B, and C zone boundaries of the
-chart.
d. Plot the 25 sample means on the
-chart and use the six pattern-analysis rules to determine whether the process is under statistical control.