Many fast-food restaurants use automatic soft-drink dispensing machines that fill cups once an order is placed at a drive-through window. A regional manager for a fast-food chain wants to determine if the machines in his region are dispensing the same amount of product. He samples four different machines and measures a random sample of 16-ounce drinks from each machine.

(a) Do the data indicate that the mean amount dispensed from the machines is not the same? Use an a = 0.05 level of significance.

(b) Use Tukey’s test, if necessary, to determine which pairwise means differ using a familywise error rate of a = 0.05.

(c) Draw boxplots of the four treatment levels to support your conclusions in parts (a) and (b).

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