a. Verify that the average distance per response d_{av} = 5.1 miles, the average
speed per response S_{av} =
12.5 miles/hr, and the average time per response t_{av} = 19.1 minutes.

b. Intuitively, explain why (d_{av}/S_{av}) x (60
minutes/hr) = 24.48 minutes is greater than t_{av} = 19.1 minutes.

c. If we compute a weighted average speed S_{wt}, where the
weights sum to 1 and are proportional to the *times* driven at each speed, we find S_{wt}
= 16.03 miles/hr. We find that (d_{av}/S_{wt} x 60 minutes/hr) = t_{av}
= 19.1 minutes. Why is this a correct procedure?