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Hourglass Time Puzzle

wooden hourglass riddleHourglass Time Puzzle - 25 December

There are 2 sand hourglasses.
The small one can measure 5 hours and the large one can measure 7 hours.

How can we measure 16 hours with 2 sand hourglasses running together ?

For Solution : Click Here


  1. Run both for 5 hours (5). Invert the 5 hour glass and let the 7 hour glass runs out (5+2 = 7). Now invert each of the 7 hour glass AND the 5 hour glass (5+2+3 = 10). Now the 7 hour glass has 4 on top and 3 on the bottom and the five hour glass has 5 on top. Invert the 7 hour glass and run 3 hours out (5+2+3+3 = 13). Now invert the five hour glass and run out the remaining three hours ... 5+2+3+3+3 = 16).

    1. simple one is below see dude :P :D

  2. run 5 three times =5x3= 15hrs
    at this instant 7hrs glass (7x2=14 complete) means 1hrs sand is full in 7hrs glass at 3rd chance...
    so invert it
    now 15+1hr= 16hrs :) :)

    1. what you have suggested is elegant and correct enough

    2. why it is wrong ?? :O
      it is right....
      5 wale se jb 15hr measure ho jayega us time 7hr wale se bhi 15hr ho jayenge aur u know wo 3rd chance mein hoga /... 2 chance mein 14hrs nd 3rd chance mein 1hr to usko invert kr denge

    3. 5+5+5=15hr
      7+7+1=15hr (7hr sand wale glass se )
      ismein 1hr ki sand niche jayegi jb 15hr ho jayenge ..kyoki 7ek aur 7 dusre to teesri bar mein 1hr ... to jo ye 1hr wali sand hai usko ulta kr dnge to 15+1hr = 16hr
      i hope u will understand :)

  3. Both hour glasses have to be running at all times until 16 hours are up. The question states, "running together"

    1. i allow them to running together dude .....
      run 5hr glass upto 15hr
      at the same time run 7hr glass also for 15hr ..
      7hr +7hr +1hr ....this 1hr sand will b in bottom(when 5hr glass complete 15hr that time 7+7complete ,, .nd 1hr sand ...then flip it.)... then flip it .. 15hr +1hr = 16hr

  4. (5 & 7 here represent corresponding hour glasses)
    Start 5+7
    When 5 is over: This is time starter
    7 will continue for 2 hrs
    Now use two times 7 to get 2+7+7=16 hrs.

    1. its must running together dude that not the solution if the condition need is running together