Assume the time Thomas takes to walk to campus is a normal random variable with a mean of 15 minutes and variance of 4 minutes. Assume the time Natalie takes to walk to campus is a normal random variable with a mean of 20 minutes and variance of 9 minutes. Assume these times are the same walking back from campus and that the time each takes to walk to campus is independent of the time each takes to walk back from campus.

However, since Thomas and Natalie know each other, if they happen to meet during a walk to or from campus this can affect their times.

The correlation between their times, whether to or from campus, is estimated at 0.25.

1. Describe the distribution of the total time Thomas and Natalie combined take to walk to and from campus.
2. What is the probability that on any given walk to and from campus, their total combined time exceeds an hour and 15 minutes?
3. Thomas and Natalie both come to campus each day of the week, Monday through Friday. What is the probability that the average total combined time for each day exceeds an hour and 15 minutes?