Perfect EggsMath brain teasers require computations to solve.
For his breakfast, Mr Stone likes an egg that has been boiled for exactly 9 minutes. He has two egg timers (those with sand in them), one that runs for 4 minutes and one that runs for 7 minutes. How can he use these timers to boil his egg?
AnswerStart both egg timers. When the 4 minute timer runs out, turn it over. When the 7 minute timer runs out turn it over. When the 4 minute timer runs out again the 7 minute timer has been running for 1 minute. Turn it over once again. When it stops the egg is done.
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