11.1 Scrap rates per thousand (parts whose   defects cannot be reworked) are compared for 5 randomly selected days at   three plants. Does the data prove a significant difference in mean scrap   rates?   ScrapRate    Plant A  Plant B  Plant C   11.4 11.1 10.2   12.5 14.1 9.5   10.1 16.8 9   13.8 13.2 13.3   13.7 14.6 5.9        Instructions:   Use MegaStat, MINITAB, or another software package to   perform Tukey’s test for significant pairwise differences. Perform the test   using both the 5 percent and 1 percent levels of significance.        Instructions:   For each data set: (a) State   the hypotheses. (b) Use   Excel’s Tools > Data   Analysis (or MegaStat or MINITAB) to perform the one-factor ANOVA, using α = .05. (c)   State your conclusion about the population means. Was the decision close? (d)   Interpret the p-value   carefully. (e) Include a plot of the data for each group if you are using   MegaStat, and confidence intervals for the group means if you are   using   MINITAB. What do the plots show?    

     11.5   Refer to Exercise 11.1. Which pairs of mean scrap rates differ significantly   (3 plants)?