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Thursday, February 8, 2007

You have eight balls all of the same size

You have eight balls all of the same size. Seven of them weigh the same, and one of them weighs slightly more. How can you fine the ball that is heavier by using a balance and only two weighings?
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3 comments:

  1. AnonymousFebruary 14, 2007 at 8:25 PM

    Choose 6 balls and weigh 3 against 3
    - if they weigh the same, you have another weighing for the remaining 2 balls and you can find the heavier one
    - if they don’t weigh the same, from the group of 3 which was heavier, choose any 2 balls and weigh them:
    - if they weigh the same, the remaining ball is the heavier one; otherwise you just found the heavier one by weighing the 2 chosen balls

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  2. AashiMarch 17, 2012 at 7:41 AM

    Take all balls and weigh 4 against 4.
    -obviously the side which weighs more has the ball whose weight is slightly more.
    -again i'll divide those 4 balls into 2-2 and repeat the same procedure and narrow it down to 2-2

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    Replies
    1. AnonymousAugust 25, 2012 at 4:11 AM

      it says in two weighings, this will require three or more than two weighings

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