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A riddle

  1. May 12, 2013 #1
    You have got two buckets of capacity 3 litres and 5 litres each and a tap. How will you exactly measure out 4 litres of water with the help of two buckets and the tap.
     
  2. jcsd
  3. May 12, 2013 #2
    You fill up 5 liter one from the tap. Then fill up 3 liter one from 5 liter one. Then empty the 3 liter one. Then split what's left in 5 liter in two buckets. Then fill up the 3 liter one again and pour it into the 5 liter one.
     
  4. May 12, 2013 #3

    jedishrfu

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    1) fill the 5 liter and pour into the 3 liter until full leaving 2 liter in the 5 liter bucket.

    2) empty the 3 lt bucket and pour the remaining 2 lt from the 5 lt bucket into the 3lt.

    So the 3 liter bucket now has 2 liters in it.

    3) Lastly fill the 5 liter completely and then pour it into the 3liter bucket until the 3 liter bucket is full.

    Since the 3 liter bucket had 2 liters in it then you've out 1 liter so that what remains in the 5 liter bucket is 4 liters.
     
  5. May 12, 2013 #4

    Danger

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    I'd calculate the height of 4 litres in the confines of the 5 litre bucket, then draw a line at that point and fill to there using the 3 litre bucket as a source.
     
  6. May 12, 2013 #5

    jedishrfu

    Staff: Mentor

    so we have the OP solution: ask someone on PF

    and the caveat emptor solution: kholdstare's split the difference

    and the greek solution (compass and straight edge only): mine

    and the high-tech engineering solution: Danger's

    we still need a management solution and a CEO solution to complete the picture.

    Of course VP Biden could step in at anytime with a shotgun solution but we won't consider that option for now :-)
     
  7. May 12, 2013 #6

    Curious3141

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    Management solution: Set up an interdepartmental cross-disciplinary committee with broad terms of reference to study the problem. Outsourcing is an acceptable option, preferably to a third world country where buckets, natural water sources and cheap labour are already plentiful, obviating the need for a budget to procure these.

    CEO solution: CEO admits to not being able to solve the problem, and not even having foreseen that such a problem might exist. Therefore, regretfully, the CEO immediately resigns, accepting the previously agreed-upon golden parachute to the tune of $50 million USD and another plum CEO job offer in a rival company.
     
  8. May 12, 2013 #7

    Danger

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    I will mention two caveats to my answer.
    1) It was partially a management response because there is no need for the 3-litre bucket, but since it's there it must be used.
    2) It was purely theoretical because I have absolutely no idea of how to do the math.
     
  9. May 12, 2013 #8

    Office_Shredder

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    The Apple solution is to insist the 3 liter bucket is good enough and if you aren't getting 4 liters of water from it it's because you're holding it wrong
     
  10. May 13, 2013 #9

    Curious3141

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    They also insist that you fill it only with AppleTM water otherwise all warranty coverage on the bucket is void.
     
  11. May 13, 2013 #10

    Danger

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    But that won't happen.
     
  12. May 13, 2013 #11
    Using a special hose attachment that splits the stream and shapes it into two hexagons because, for whatever reason, a standard "circular" stream isn't as efficient.
     
  13. May 13, 2013 #12

    Danger

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    Do I see a patent for a spin-off from condom technology in your future? Maybe a urinal-based game of some sort?
     
  14. May 13, 2013 #13
    This may prove to be useful in visualising your answer.

    www.youtube.com/watch?v=lZ64IR2bz5o
     
  15. May 14, 2013 #14

    Curious3141

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    I thought of this movie too - I remember this scene very well (along with the Saint Ives riddle).

    There are multiple solutions, of course. I think I found 3.
     
  16. May 14, 2013 #15

    pffft... no! Whatever could have made you think that? :uhh:
     
  17. May 14, 2013 #16

    Danger

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    Nothing in particular. My mind wanders sometimes...
     
  18. May 14, 2013 #17
    Also, one solution.

    Fill the five liter bucket completely

    Pour out three liters (where else?)

    Fill the 5 liter bucket to twice the level of the remaining water (assuming it's perfectly cylindrical).
     
  19. May 15, 2013 #18

    Danger

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    That's pretty clever, Mr. Trackman, but... have you ever seen a cylindrical bucket?
    My uncle owned a bucket store... I had to make buckets every day after school... we made wood buckets and steel buckets and I even made one out of a dead badger once... and I gotta tell you that not a single one of 'em was cylindrical.
     
  20. May 15, 2013 #19
    The internal (or external, for that matter) shape of the bucket was never specified, though! :biggrin:
     
  21. May 15, 2013 #20

    Danger

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    Oh, sure... get technical about it... :rolleyes:
     
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