1.The following data contains the number of friends on Facebook for an SRS of 20 Facebook users from a large university.

99 148 158 126 118 112 103 111 154 90 120 127 137 74 85 104 106 72 119 160

(a) Manually compute the mean, standard deviation, standard error and margin of error for the 95% confidence interval. (Use R to find the appropriate critical t* value)

(b) Manually compute the 95% confidence interval for the mean number of friends on Facebook for Facebook users at this large university.

2.A crossover study was conducted to investigate whether oat bran cereal helps to lower

serum cholesterol in hypercholesterolemic males. Fourteen such individuals were randomly placed on a diet that included either oat bran or corn flakes; after two weeks, their low-density lipoprotein (LDL) cholesterol levels were recorded. Each man was then switched to the alternative diet. After a second two-week period, the LDL cholesterol level of each individual was again recorded. The data from this study are shown below:

Sub. Corn flakes Oat bran

1 4.61 3.84

2 6.42 5.57

3 5.4 5.85

4 4.54 4.8

5 3.98 3.68

6 3.82 2.96

7 5.01 4.41

8 4.34 3.72

9 3.8 3.49

10 4.56 3.84

11 5.35 5.26

12 3.89 3.73

13 2.25 1.84

14 4.24 4.14

(a) Are the two samples of data paired or independent?

(b) What are the appropriate null and alternative hypotheses?