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mo

Fri Feb 01, 2008 6:49 pm


another riddle

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you have 10 pennies
each penny identical, but one weighs more than the others
so 9 are the same and one is different
you also have a scale(no numbers or anything)
where it has two sides and you put the coins on each side to see which pile weighs more
you can only use the scale twice
figure out which penny is different


and if you have seen this riddle somewhere else please dont answer it


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Zampano

Fri Feb 01, 2008 6:54 pm


Re: another riddle

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You made a mistake I think. That's 9 pennies, not 10. When there's more 3 to the power of the number of weighings, it fails.


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mo

Fri Feb 01, 2008 6:58 pm


RE:another riddle

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sorry folks question is 9 pennies instead of 10

my bad


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fishtastic

Fri Feb 01, 2008 6:59 pm


RE:another riddle

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10 pennies??
how do you solve for 10?


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fishtastic

Fri Feb 01, 2008 7:00 pm


Re: another riddle

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OIC..
3 3 3


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mo

Fri Feb 01, 2008 7:01 pm


RE:another riddle

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explain more thoroughly


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pistolpete

Sun Feb 17, 2008 11:43 pm


RE:another riddle

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You divide the 9 coins into 3 piles, place any 2 on either end of the scale. If the scale is unbalanced you know the side which contains the heavier coin, and if it stays balanced you know the pile that you left alone contains the coin. Take whichever pile you know contains the heavy coin and repeat the same process to find the heavy coin in that pile of 3. zomg its just like recursion :)


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Mackie

Mon Feb 18, 2008 12:12 am


RE:another riddle

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Did you just say 'Zomg'?


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ericfourfour

Mon Feb 18, 2008 1:02 am


RE:another riddle

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0 = regular coin
1 = heavier coin
Randomize coins: 000010000

Divide into groups:
    Group 1 = 000
    Group 2 = 010
    Group 3 = 000
Scale groups 1 and 2: 1 < 2.
Group 2 contains heavier coin.

Divide into groups:
    Group 1 = 0
    Group 2 = 1
    Group 3 = 0
Scale groups 1 and 2: 1 < 2.
Group 2 contains heavier coin.