Question: Three supermarket chains in the Denver area each claim to have the lowest overall prices. As part of an investigative study on supermarket advertising, the Denver Daily News conducted a study.

First, a random sample of nine grocery items was selected. Next, the price of each selected item

was checked at each of the three chains on the same day. At the .05 significance level, is there a

difference in the mean prices at the supermarkets and for the items?