A puzzle by Polish mathematician Paul Vaderlind:
If a blacksmith requires five minutes to put on a horseshoe, show how can 8 blacksmiths shoe 10 horses in less than half an hour?
The catch: A horse can stand on three legs, but not on two.
(In reply to re: solution
Here is an arrangement that minimizes changes.
Each blacksmith changes only once, and works on only two horses.
4 horses are shoed by 1 smith, and the rest by 2.
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