Whole Grains Inc. uses statistical process control to ensure that its health-conscious, low-fat, multigrain sandwich loaves have the proper weight. In order to calculate 3σ control limits for both means and ranges, based on periodic process sampling, the following weights information (in ounces) were recorded.
Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Sample 8
Loaf # 1 6.5 6.1 5.7 6.7 5.6 5.4 6.0 5.9
Loaf # 2 6.2 6.7 6.4 5.9 6.0 5.8 6.2 6.4
Loaf # 3 6.6 6.3 6.2 6.1 6.4 6.6 6.4 6.3
Loaf # 4 5.8 6.0 6.1 6.3 5.9 6.1 6.0 5.9
a) Obtain the upper limit, center line, and lower limit for both charts.