2.

If, in a dataset with 441 observations, you compute a sample mean of 6 and a sample variance of 4, the corresponding 95% confidence interval for the population mean will be approximately:

a. (3.44,4.56). b. (5.23.6.74). c. (2.64,3.75). d. (5.63,6.37). e. None of the above

3.

Consider the table below, which contains the joint distribution of weather and commuting times. What is the marginal probability of a short commute? a. .22. b. .46. c. .68. d. .50. e. None of the above.

	Rain(X=0)	No Rain(X=1)
Long Commute(Y=0)	0.22	0.10
Short Commute(Y=1)	0.22	0.46

4.

Using the same table as in question 3, what is the probability of a short commute, given that it will rain? a. .50. b. .22. c. .82. d. .68. e. None of the above.