Thirty graduate students were asked how many credit hours they were taking in the current quarter.

Student Number	Credit Hours
1	4
2	11
3	3		Students' responses to how many credit hours
4	5		they were taking in the current quarter
5	7
6	11
7	10
8	8
9	12
10	12
11	6
12	6
13	12
14	7
15	8
16	5
17	6
18	7
19	10
20	11
21	12
22	8
23	6
24	10
25	11
26	3
27	5
28	12
29	8
30	11

1. Calculate the mean, median, standard deviation, variance, and range for this sample using Excel. Write a sentence explaining what each measure means.
2. What is the standard error of the mean based on the data?
3. What would be the best point estimate for the population credit hours? ("Population" refers to all graduate students' credit hours in the universe.)
4. What is the 95% confidence interval for the means of credit hours? What is the 90% confidence interval?