A manufacturer of dustless chalk instituted a quality control program to monitor chalk density. The sample standard deviations of densities for 24 different subgroups, each consisting of n = 8 chalk specimens, were as follows:
.204 .315 .096 .184 .230 .212 .322 .287
.145 .211 .053 .145 .272 .351 .159 .214
.388 .187 .150 .229 .276 .118 .091 .056
Calculate limits for an S chart, construct the chart, and check for out-of-control points. If there is an out-ofcontrol point, delete it and repeat the process