Graphite production, 10 lanes. The same graphite manufacturer from Exercise 21 uses an alternative process to make rolls. For this process the data are separated into 10 lanes—a sample consists of one roll from each lane.

The results of 25 samples are shown in the table at the top of the page.

a) Using the same mean and standard deviation as given in Exercise 21, create an X chart for these samples.

b) Using the mean and standard deviation as in Exercise 21, create an R chart for these samples.

c) Is the company’s process for making f lexible graphite sheets in control?

d) Are all of these rolls within the specification limits?