Lisa Grattan, a financial analyst for a small investment firm, collects annual stock return data for 10 firms in the energy industry, 13 firms in the retail industry, and 16 firms in the utilities industry. A portion of the data is shown in the accompanying table.

EnergyRetailUtilities

12.5........................6.6.................3.5

8.2..........................7.4.................6.4

⋮..............................⋮.....................⋮

6.9..........................7.9.................4.3

In a report, use the sample information to:

1. Determine whether significant differences exist in the annual returns for the three industries at the 5% significance level.

2. Construct 95% confidence intervals for the difference between annual returns for each pairing using Tukey's HSD method.

3. Evaluate which means (if any) significantly differ from one another using the results from part 2.