Lowering the thickness of an expensive blow-molded container. Refer to the Quality (March 2009) study of a plant that produces a high-volume, blow-molded container, Exercise 13.33 (p. 13-41). Recall that the quality manager at the plant wants to lower the average thickness for the expensive layer of material and still meet specifications. Specification limits for individual thickness values are .10 to .30 millimeter.

a. Find the standard deviation of the process data.

b. Calculate the capability index, Cp, for the process and interpret the result.

c. Compare the LCL of the process (from Exercise 13.33) with the LSL. Does this imply that the average thickness of the material can be lowered and still meet specifications?