of breaking strengths now being produced will be used to calculate the values of the charts’

central lines and control limits. The latter will be 1.75-sigma limits, because the cost of a type 2 error is

quite high.

To estimate the values of mu (pop. mean) and sigma, an analyst draws 25 samples;

each sample contains 20 leaders. The leaders are tested, and the sample averages and

ranges are computed. The sum of the 25 sample averages is found to be 205.6 pounds, and the sum of

the 25 sample ranges is found to be 51.3 pounds.

It so happens that two sample averages and three sample ranges exceed the first set of limits The values of the two sample averages are 10.9 and 7.7 pounds; the values of the three sample rangesare 3.8, 4.5, and 1.2 pounds

2nd limits calculated:none of the remaining sample averages but one of the remaining sample ranges exceed the 2nd limits.

all values fall within 3rd lim