November 2020
Problem of the Month
Railroad Bridge Part 1
Frank is walking across a one mile long railroad bridge ignoring his mother's commands and the signs on the bridge. He has
walked 1/4 of a mile when he looks back and sees a train coming. The train is 3/4 of a mile from the beginning of the bridge.
Frank's top running speed is a six minute mile. Which way should he run?
Determine the answer to the question if the train is coming at the following speeds:
(1) 25 mph
(2) 35 mph
(3) 20 mph
Be complete and show your work.
Extra Credit:
Determine all possible integer train speeds which result in Frank's
(a) escaping in both directions
(b) escaping only by running toward the train and
(c) escaping in neither direction