Studies show that smaller class sizes have a direct impact on student success. Researchers selected a random sample of 28 elementary school classrooms across the United States and found that the mean class size was 23.81 students with a standard deviation of 1.4 students. They also selected a random sample of 63 high school classrooms across the United States and found that the mean class size was 23.05 with a standard deviation of 1.4 students. Check each of conditions that have been met to construct a two-sample t confidence interval for the difference in mean class sizes between elementary and high schools. The samples are independent The sample of elementary classrooms is random The sample of high school classrooms is random The sample size for elementary classrooms is at least 30 The sample size for high school classrooms is at least 30 The average classroom size is at least 10