A machine at the Dream Mix Company fills boxes with cereals. The labeled weight of the boxes is 9.4 ounces, with +/- 0.9 ounce. The company wants to construct 3-sigma control charts to monitor the filling process and make sure the box weights are in control. The quality control department for the company sampled five boxes every 2 hours for six cycles. The sample observations are as follows.
Sample Box Weights
1 9.06 9.13 8.97 8.85 8.46
2 8.52 8.61 9.09 9.21 8.95
3 9.35 8.95 9.2 9.03 8.42
4 9.17 9.21 9.05 9.01 9.53
5 9.21 8.87 8.71 9.05 9.35
6 8.74 8.35 8.5 9.06 8.89
a) Construct 3sigma control charts.
b) The quality control department collected observation for another six cycles. Plot the corresponding values on control charts.