A consumer advocate researches the length of life between two brands of refrigerators, Brand A and Brand B. He collects data (measured in years) on the longevity of 40 refrigerators for Brand A and repeats the sampling for Brand B. The data set, labeled Refrigerator_Longevity, can be found on the text website.

a. Specify the competing hypotheses to test whether the average length of life differs between the two brands.

b. Using the appropriate commands in Excel, find the value of the test statistic. Assume that σ2A = 4.4 and σ2B = 5.2. What is the p-value?

c. At the 5% significance level, what is the conclusion?