Wrong, But Useful: Episode 8

| Oct 24, 2013 min read

In this month’s Wrong, But Useful, @icecolbeveridge (Colin Beveridge in real life) and @reflectivemaths (Dave Gale when he’s at home)…

The new puzzle, courtesy of @sherriburroughs:

Dave is, recklessly, walking across a railway bridge1 and is three-eights of the way across when - disaster! He hears a train coming. It’s the kind of train that travels at a constant speed of 100 km/h.
If he runs towards the train, he gets off of the bridge just in time; if he runs away from the train, he also gets off the bridge just in time.
How fast does he run?

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  1. In discussing the problem, I flippantly and incorrectly say “maybe the bridge is a mile long” - there is no information about the length of the bridge. ↩︎