1. For an analysis of variance comparing four treatments with n = 15 in each treatment, what would be the df for F-test? C 4, 60 3, 56 C 4, 56 C 3, 60 2. In the population of drivers, the mean number of traffic violations in the last 10 years is 5.2. In a random sample of 300 drivers, the mean number of moving violations is 4.25. The difference between 5.2 and 4.25 is due to C a statistical error C a parametric error a sampling error better driving skills among the drivers in the sample