Here it is: You have two sand-filled egg timers, one for 9 minutes and one for 2 minutes. How can you use them to time a 5-minute egg?
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You start them both at the same time and when the two minute egg had to be turned twice you immediately have 5 minutes left
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Flip both sand-filled timers, so both are running.
When the two minute timer is done flip it so it runs again.
When the two minute timer is done for the second time, put the egg in the water. You have five minutes left on the 9 minute timer.
When the two minute timer is done flip it so it runs again.
When the two minute timer is done for the second time, put the egg in the water. You have five minutes left on the 9 minute timer.
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put on the 9 minute timer, and put on the 2 minute timer at the same time.
after the 2 minute timer is up flip it again.
when the 2 minute timer is up, the time on the 9 minute timer would be the time for a 5 minute egg.
9 minus 4 equals 5
after the 2 minute timer is up flip it again.
when the 2 minute timer is up, the time on the 9 minute timer would be the time for a 5 minute egg.
9 minus 4 equals 5
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turn both over and watch for the 2 minute one to run out twice as soon as the second run on the 2 min sand timer goes pop the eggs in and wait for the remaining 5 minutes in the large hour glass to run out
2+2=4-9=-5
2+2=4-9=-5