Referring to the data of Problem 17.24 on page 736, stored in SpWater, the researchers stated, "Some of the benefits of a capable process are increased customer satisfaction, increased operating efficiencies, and reduced costs." To illustrate this point, the authors presented a capability analysis for a spring water bottling operation. One of the CTQ variables is the amount of magnesium, measured in parts per million (ppm), in the water. The LSL and USL for the level of magnesium in a bottle are 18 ppm and 22 ppm, respectively.
a. Estimate the percentage of bottles that are within specifications.
b. Compute the Cp, CPL, CPU, and Cpk.