12.25 Monitoring packaged products.

To control the fill amount of its cereal products, a cereal manufacturer monitors the net weight of the product with and charts using a subgroup size of . One of its brands, Organic Bran Squares, has a target of 10.6 ounces. Suppose that 20 preliminary subgroups were gathered, and the following summary statistics were found for the 20 subgroups:

Assume that the process is stable in both variation and level. Compute the control limits for the and charts.