Energy Consumption: Constructing an Chart Use samples of size 3 by combining the first three values for each year and combining the last three values for each year.

Using the eight samples of size 3, construct an chart and determine whether the process mean is within statistical control. If it is not, identify which of the three outof-control criteria lead to rejection of a statistically stable mean. What is a practical effect of not having this process in statistical control? Give an example of a cause that would make the process go out of statistical control.

Constructing Control Charts for Aluminum Cans. Exercises 5 and 6 are based on the axial loads (in pounds) of aluminum cans that are 0.0109 in. thick, as listed in Data Set 20 in Appendix B. An axial load of a can is the maximum weight supported by its side, and it is important to have an axial load high enough so that the can isn’t crushed when the top lid is pressed into place. The data are from a real manufacturing process, and they were provided by a student who used an earlier edition of this book.