Are your pupils creative enough to solve this one? How fast are the trains?

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1 Response

  1. Alex Scotney says:

    I heard this problem on the TES podcast, and having spent a number of hours trying to solve it, I was a little disappointed with the eventual answer. Am I right in saying that if the total distance is x, the problem only works if the faster train is travelling at exactly (1/3)x miles per hour? E.g. if the distance is 300 miles, the faster train must be travelling at 100mph. At any other speed, the remaining time will not allow the trains to meet at the point where one is 1 hour away and the other is 4 hours away – e.g. taking 300 miles as the distance again, if train A travels at 20mph and train B at 10mph, when train A is 1 hour away (after 14 hours) it will have travelled 280 miles, whereas train B will only have travelled 140 miles. Indeed, by the time train B is 4 hours away, train A will long since have arrived!