201. Bob the Quality Control Engineer is studying the mass of cookie bags again. Thirty samples of size 6 are drawn at one-hour inter- vals, and the following data are obtained: 30 30 =7524.00 g r=114.03 g i=1 (a) Determine and T. (b) Assuming the process is in control, esti- mate the process mean and standard devia- tion. (c) Determine control limits for X and R con- trol charts.