Sand Timer Puzzle


You have two sand-timers, one of 11 min and another of 7 min.
How will you measure 15 min using them?


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  • 1 Answer(s)

    Start both the timers viz. 7min & 11 min.

    When 7min timer completes, just reverse it so that it starts again..

    When 11min completes, just reverse the 7min timer again (4 min would have lapsed = 11 – 7)

    Wait for 7min timer to complete; it will take 4 min… totalling 11 + 4 = 15 minutes!

    bhola99 Expert Answered on 17th February 2020.
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