Egg timers

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Here is a variation on one of Richard Wiseman's Friday puzzles.


For dinner you decide to make a soft boiled ostrich egg. Problem is, an ostrich egg needs to boil for exactly seven minutes. After searching through your kitchen drawers, you find two hour-glass-style egg timers: one for three minutes, the other for five minutes. Is it possible to time exactly seven minutes using these timers? Is it possible to do so without any preparation?

See also


Richard Wiseman's blog