Referring to Exercise 18-15, suppose the process remained in control for the next 40 hours.

The thickness measurements for hours 41 through 43 are as follows:

Hour 41 0.764 0.737 0.724 0.716 0.752 Hour 42 0.766 0.785 0.777 0.790 0.799 Hour 43 0.812 0.774 0.767 0.799 0.821

a. Based on these data and the two control charts, what should you conclude about the process? Has the process gone out of control? Discuss.

b. Was it necessary to obtain your answer to Exercise 18-15 before part a could be answered? Explain your reasoning.