Please show to solution for this question.

Control charts are to be constructed for samples of size n : 4, and a? and S are computed for each of 21 preliminary samples as follows: 21 21 2 it = 4683 25: = 285.18 t=1 i=1 (a) Calculate control limits and center line of both xbar and 5 charts. (b) If process is in control, estimate process mean and standard deviation