Control charts arc lo be used to monitor the thicknesses of glass sheets. DS 16.3.3 contains the

Question:

Control charts arc lo be used to monitor the thicknesses of glass sheets. DS 16.3.3 contains the thicknesses in mm of random samples of n = 4 glass sheets collected at k = 24 different times.
(a) What -chart and R-chart would you recommend be used?
(b) What conclusion would you draw if in the future a sample x1 = 3.12, x2 = 2.96, x3 = 2.91, and x4 = 2.88 is obtained?