Three brands of batteries are under study. It is suspected that the lives (in weeks) of the three brands are different. Five randomly selected batteries of each brand are tested with the following results (treat this as completely randomized design):

Table 1: Weeks of Life
Brand1 Brand2 Brand3
100 76 108
96 80 100
92 75 96
96 84 98
92 82 100

Answer the questions based on the observed data:
(a) Are the lives of these brands of batteries different?
(b) Analyze the normality assumption and state your conclusion.
(c) Check the constant variance assumption and state your conclusion.
(d) Construct a 95% simultaneous confidence interval for all pairs of means using Tukey's method.
(e) From (d), which brand has the shortest life?
(f) For the brand selected in (e), the manufacturer decides to replace without charge any battery that fails in less than 80 weeks, what percentage of batteries of this brand would the company expect to replace?