Electrobat, a battery manufacturer, is investigating how storage temperature affects the performance of one of its popular deep-cell battery models used in recreational vehicles. Samples of 30 fully charged batteries were subjected to a light load under each of four different storage temperature levels. The hours until deep discharge (meaning ≤ 20% of charge remaining) was measured. A portion of the data is shown in the accompanying table.

0 degrees F30 degrees F60 degrees F90 degrees F

3......................6.........................12...........................12

5......................8.........................13...........................15

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

4......................9.........................9.............................15

a. Use Excel to generate the appropriate ANOVA table at the 5% significance level.

b. At the 5% significance level, what is the conclusion of the test? What about the 1% significance level?

c. If significant differences exist, use Tukey's HSD method at the 5% significance level to determine which temperature levels have different mean discharge times.