Reconsider the copper-content measurements in Exercise 15-8. Given that the specifications are at 6.0 ± 1.0, estimate PCR and PCR_kand interpret these ratios.

Exercise 15-8

The copper content of a plating bath is measured three times per day, and the results are reported in ppm. The xÌ… and r values for 25 days are shown in the following table:

Day Day 1.21 1 5.45 14 7.01 1.45 0.95 1.37 5.39 15 5.83 3 6.85 1.43 16 6.35 1.04 6.74 1.29 17 6.05 0.83 5 5.83 1.35 18 7.11 1.35 7.22 1.09 0.88 19 7.32 6.39 0.92 20 5.90 1.22 8. 6.50 1.13 21 5.50 0.98 1.25 22 9. 7.15 6.32 1.21 6.55 0.76 10 5.92 1.05 23 11 6.45 0.98 24 5.90 1.20 5.95 1.19 12 5.38 1.36 25 13 6.03 0.83