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This is an experiment to determine the effect of CzF ow rate on the uniformity of the etch on a silicon wafer used in integrated circuit manufacturing. Three ow rates are used in the experiment, and the resulting uniformity (in percent) for six replicates follows. 125 2.7 4.6 2.6 3.0 3.2 3.3 160 4.9 4.6 5 .0 4.2 3.6 4.2 200 4.6 3.4 2.9 3.5 4.1 5.1 (a) Does C2F6 ow rate a'ect etch uniformity? Construct box plots to compare the factor levels and perform the analysis of variance. Use {1 = 0.05. (b) Do the residuals indicate any problems with the underlying assumptions? Please draw three plots as shown in class: 1) normal probability plot of the residuals; 2) residuals versus FLOW; 3) residuals versus tted value