During long production runs of canned tomatoes, the average weights (in ounces) of samples of five cans of standard- grade tomatoes in pureed form were taken at 30 control points during an 11-day period. These results are shown in the table. When the machine is performing normally, the average weight per can is 21 ounces with a standard deviation of 1.20 ounces.
Compute the upper and lower control limits and the centerline for the  chart.