Each of three supermarket chains in the Denver area claims to have the lowest overall prices. As part of an investigative study on supermarket advertising, a local television station conducted a study by randomly selecting nine grocery items. Then, on the same day, an intern was sent to each of the three stores to purchase the nine items. From the receipts, the following data were recorded. At the 0.100 significance level, is there a difference in the mean price for the nine items between the three supermarkets?
Item Super Ralph's Lowblaws
1 $2.32 $1.25 $1.25
2 2.40 1.80 1.87
3 2.10 3.10 3.10
4 2.30 1.87 1.87
5 1.21 1.37 1.37
6 4.04 3.05 1.72
7 4.32 3.52 2.22
8 4.15 3.08 2.40
9 5.05 4.15 4.21
1. State the null hypothesis and the alternate hypothesis.
2. What is the decision rule for both?
3. What is your decision regarding the null hypothesis?
4. Is there a difference in the item means and in the store means?