In a sample of 25 classes, the following numbers of students were observed.

Class	Number of students		Class	Number of students
1	40		14	37
2	50		15	35
3	42		16	44
4	20		17	10
5	29		18	40
6	39		19	36
7	49		20	20
8	46		21	20
9	52		22	29
10	45		23	58
11	51		24	51
12	64		25	54
13	43

1. Calculate the mean, median, standard deviation, variance, and range for this sample.
2. What is the standard error of the mean based on this information?
3. What would be the best point estimate for the population class size?
4. What is the 95 percent confidence interval for class size? What is the 90 percent confidence interval? Does the difference between these two make sense?