Four tire brands (A, B, C, D) were tested to see whether they differed in terms of mean tread life(measured in thousands of miles). The data gathered for 14 total measurements are as follows:
brand <- c('A','A','A','B','B','B','C','C','C','C','D','D','D','D')
life <- c(53.0,49.2,49.6,52.5,52.1,51.9,51.2,51.7,47.8,49.1,50.9,50.1,50.1,55.2)
(a) fill in an ANOVA table with the appropriate numerical values.
(b) Test whether the population mean tread life is equal for the three brands, using alpha = 0.10.