Two trains travel toward each other on the same track, beginning 100 miles apart. One train travels at 40 miles per hour; the other travels at 60 miles an hour. A bird starts flying in the same place as the fast train, flying at a speed of 90 miles per hour. When it reaches the slower train, it turns around flying the other direction at the same speed. When it reaches the faster train again, it turns around and so on. When the trains meet how far will the bird have flown?
90 miles ... as the trains will meet after exactly one hour, and if the bird is flying at 90 mph he will have travelled 90 miles assuming no speed is lost in turning ! ;0)