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Homework Help: I bet you cant figure this one out

  1. Sep 18, 2006 #1
    I bet you cant figure this one out!!

    Ive been working on this problem for extra credit in one of my classes all morning and its driving me nuts. The problem is "you are given 12 pennies, they all weight exactly the same except one, your a given a balance scale and need to figure out if the penny that is different is lighter or heavier than the rest, and you can only use the scale three times" I hope someone can help me out on this one.

  2. jcsd
  3. Sep 18, 2006 #2
    Hi schwic,
    I don't why you have posted this old puzzle in the physics section. Just search the Brain Teasers forum, and you're bound to come across many threads about the same or a similar puzzle.
  4. Sep 18, 2006 #3

    Andrew Mason

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    Homework Helper

    Do a binary search on the pennies. Divide them into 6 and 6 and take the heavier 6. Split those up and take the heavier 3. I will leave you to determine how you do the last weigh.

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