The copper content of a plating bath is measured four times per day, and the results are reported in parts per million. The table gives the daily sample mean daily sample standard deviation s. Note that E(s) = cσ , where = 0.92 and σ is the
true standard deviation.
Give the upper control limit (UCL) and lower control limit (LCL) for a 3-sigma control chart.
Is the process in control? (Y/N) If so, explain why. If not, for which day(s) was it out of control?