3

Based on a random sample of 13 tire changes, the meantime to change a tire on a Boeing 777 has a mean of 59.5 minutes with a standard deviation of 8.4 minutes. For 10 tire changes on a Boeing 787, the meantime was 64.3 minutes with a standard deviation of 12.4 minutes. To test for equal variances in a two-tailed test at a = .10, the critical values are 3.07 and 0.398 3.73 and 0.228 3.07 and 0.357 2.51 and 3.67