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 table) Brand A 16 14 Brand B 16 18 20 B 17 Click here for the Excel Data File Assume that is the mean longevity for Brand A and is the mean longevity for Brand B. a. Specify the competing hypotheses to test whether the average length of life differs between the two brands. O Ho: H1-H2=0; HA: H1-H2*0 O Ho: H1-H220; H: 1-20 OHO: H1 H20; HA H1-H2>0 b-1. Calculate the value of the test statistic. Assume that 24.4 and 2 = 5.2. (Negative value should be indicated by a minus sign. Round final answer to 2 decimal places.) Test statistic 3 Brand A Brand B 1 16 16 5 14 20 17 18 7 19 15 3 19 19 20 21 01234567800-234567890-234567890-NM 12 21 16 18 19 20 14 19 15 15 13 13 13 16 15 15 15 19 12 17 15 18 16 16 17 16 16 20 16 12 16 19 19 16 16 15 16 20 16 18 21 14 18 17 21 18 15 17 20 18 13 16 18 18 18 14 21 15 16 20 16 23 18 15 16 16 18 17