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. A portion of the data is shown in the accompanying table. (You may find it useful to reference the appropriate table: z table or ttable) Brand A Brand B 13 24 22 15 12 22 Click here for the Excel Data File Assume that 1 is the mean longevity for Brand A and 2 is the mean longevity for Brand B. a. Select the competing hypotheses to test whether the average length of life differs between the two brands. Ho: H1 H2 = 0; HA: H1 - H2 * 0 He: H1 H2 = 0; HA: H1-H2 < 0 Ho: H1 H2 = 0; HA: H1-H2> 0 b-1. Calculate the value of the test statistic. Assume that o2 4.9 and ag2 5.9. (Negative value should be indicated by a minus sign. Round final answer to 2 decimal places.) Test statistic