The Federal Aviation Authority is studying the variation in the amount of time by which planes arrive late for Plane-O Air and Budget Fly. A random sample of 16 flights yielded a standard deviation of 25 minutes for Plane-O Air, while a random sample of 30 Budget Fly flights yielded a standard deviation of 18 minutes. The investigator wants to determine if Plane-O Air has a larger variation in arrival time than Budget Fly. The null hypothesis (Ho) will be rejected using a 5% significance level if the test statistic is: