Twelve samples, each containing five parts, were taken from a process that produces steel rods. The length of each rod in the samples was determined. The results were tabulated and sample means and ranges were computed. The results were:
Determine the upper and lower control limits and the overall means for -charts and R-charts. Draw the chart and plot the values of the sample means and ranges. Do the data indicate a process that is in control? Why or why not?