Chapter B.5, Problem 20AYU

Filling Machines A quality-control engineer wants to find out whether or not a new machine that fills bottles with liquid has less variability than the machine currently in use. The engineer calibrates each machine to fill bottles with 16 ounces of a liquid. After running each machine for 5 hours, she randomly selects 15 filled bottles from each machine and measures their contents. She obtains the following results:

1. (a) Is the variability in the new machine less than that of the old machine at the α = 0.05 level of significance? Note: Normal probability plots indicate that the data are normally distributed.
2. (b) Draw boxplots of each data set to confirm the results of part (a) visually.