Two trains, A and B, leave their respective starting points at the same time and travel in opposite directions. They travel at constant speeds, and pass at point M. One travels at twice the speed of the other. If one of the trains leaves five minutes late they pass at a point 2 miles from point M.
What is the speed of the slow train, in miles per hour?
Slow train is moving at 36 miles per hour; fast train at 72 miles per hour. If fast train leaves late, at the time the slow train arrives at M, the fast train has 72/12 = 6 miles yet to go. As the trains continue to proceed towards each other, the slow train goes 2 miles in the time that the fast train goes 4 miles. If the slow train leaves late, at the time the fast train arrives at point M, the slow train has 36/12 = 3 miles to go. The fast train goes 2 of the intervening miles, while the slow train goes one mile. Either way the trains meet 2 miles from M.
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