Question: A consumer advocate researches the length of life between two brands of refrigerators, Brand A and Brand B. He collects data on the longevity of 40 refrigerators for Brand A and repeats the sampling for Brand B. These data are measured in years and can be found on the text website, labeled Refrigerator Longevity.
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?