Several samples of size 4 were taken from a production line. The results were: Overall mean x ?=70 ; Average range R ¯=5.
(a) Determine the upper and lower control limits of the x ¯ chart. Please give the formulas for calculating UCL and LCL and at least one step of calculation.
(b) Determine the upper and lower control limits of the R chart. Please give the formulas for calculating UCL and LCL and at least one step of calculation.