Two boys walking in the woods decided to take a shortcut through a railroad tunnel. When they had walked 2.3 of the way through the tunnel, their worst fears were realized. A train was coming in the opposite direction, nearing the tunnel entrance. The boys panicked and each ran for a different end of the tunnel. Both boys ran at the same speed, 10 miles per hour. Each boy escaped from the tunnel just at the instant that the train would have squashed him into the rails. Assuming the trainfs speed was constant, and both boys were capable of instantaneous reaction and acceleration, how fast was the train going?
Answer: 30 miles per hour.