The manufacturer of a toner cartridge claims the mean number of printouts is 10,000 for each cartridge. A consumer advocate is concerned that the actual mean number of printouts is lower. He selects a random sample of 14 such cartridges and obtains the following number of printouts:
(a) Because the sample size is small, he must verify that the number of printouts is normally distributed and the sample does not contain any outliers. The normal probability plot and boxplot are shown. Are the conditions for testing the hypothesis satisﬁed?
(b) Are the consumer advocate’s concerns founded? Use the α = 0.05 level of signiﬁcance.
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