By Alice Lopez,2014-05-15 07:44
1. A marathon runner runs at a steady 15km/hr. When the runner is 7.5 km from the finish, a bird begins
flying from the runner to the finish at 30 km/hr. When the bird reaches the finish line, it turns around and
flies back to the runner, and then turns around again, repeating the back-and-forth trips until the runner
reaches the finish line. How many kilometre..