Starting at the same time and place, Abe and Bob race, running at velocities u(t) = 4/(t + 1) mi/hr and v(t) = 4e^-t/2 mi/hr, respectively, for t ≥ 0. 

a. Who is ahead after t = 5 hr? After t = 10 hr?

b. Find and graph the position functions of both runners. Which runner can run only a finite distance in an unlimited amount of time?