Brain Teaser

[Flametop]

Re: Brain Teaser

My guess is that they are foil wrapped chocolate coins. [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img]

[MetalGrasshopper]

Re: Brain Teaser

[ QUOTE ]
Its bags of coins.
You weigh six bags and set two bags to the side.
If the three on each side of the scale weigh equal you eliminate six bags. weigh the last two and you find the lighter one is missing a coin.

Now if you are weighing six bags three on each side and one side is lighter you take those three bags set them for the second weigh in because one is missing the coin.

Take two bags and weigh them. If they are equal your last bag is the one missing a coin or the lighter bag on the scale is missing a coin.

From years of weighing crap this is easy for me.

[/ QUOTE ]

I think you're the first one to get it right without making me read the post 10 times...nice job. dm got the answer right too, but his answer was just [img]/images/graemlins/what.gif[/img]

[MetalGrasshopper]

Re: Brain Teaser

[ QUOTE ]
[ QUOTE ]
I have 8 identical bags of coins. I know that 7 contain the same number of coins and 1 bag is missing a coin.

[/ QUOTE ]

Then the bags are not identical, therefore the question is invalid [img]/images/graemlins/laugh.gif[/img]

Begin: Put 4 bags on each side of the scale - the lighter side will be the one with the missing coin.
1st Use of the scale: Remove 2 bags from each side. If the scales are unbalanced, the lighter bag is still on the scale. If the scale balances, one of the two bags you removed from the lighter side is missing a coin.
2nd Use of the scale: If the scale is balanced with 2 bags on each side, swap one bag on the scale with one of the ones you took from the lighter side previously. If the scale is then unbalanced, the bag you put on is missing one coin. If the scale is then still balanced, the other bag you took off in the first use is missing the coin.

It's a bit of a trick question because it doesn't specify what constitutes taking a turn on the scale. Most automatically assume that if you put any bags on each side of the scale, you've used your first turn and can only take one more action (swapping bags or whatnot). In order to be a solvable puzzle, one concession must be allowed - putting all 8 bags on the scale first (IF they're not already there). Anything after that counts as the first turn.

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No, as soon as you put anything on the scale it counts as a turn, so your method requires more than 2 turns.

[AK47]

Re: Brain Teaser

Wait till you guys get a problem that involves fluids and distributing those and having to use a scale because you have no marked beakers or jars.

Done that one as well.

[fett]

Re: Brain Teaser

I take them to a CoinStar machine and let it sort it out. [img]/images/graemlins/crazy.gif[/img]

[guitarsjb]

Re: Brain Teaser

[ QUOTE ]
I take them to a CoinStar machine and let it sort it out. [img]/images/graemlins/crazy.gif[/img]

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LMAO!! I was just at my local one... [img]/images/graemlins/laugh.gif[/img]

[AK47]

Re: Brain Teaser

I just cashed in 7000 pennies a couple days ago.

[Newc]

Re: Brain Teaser

[ QUOTE ]
How would I, without opening any of the bags, determine which bag is missing the coin if I'm allowed to use the balance only twice?

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First I'd have a chat with the douchebag who said I could only use a balance, and could only use it twice [img]/images/graemlins/laugh.gif[/img]

[RacerX]

Re: Brain Teaser

Yeah, but, if you put the jet-powered bags on a treadmill runway, would they fly? [img]/images/graemlins/tongue.gif[/img]

[Flametop]

Re: Brain Teaser

[ QUOTE ]
Wait till you guys get a problem that involves fluids and distributing those and having to use a scale because you have no marked beakers or jars.

Done that one as well.

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I distribute my fluids via skeet and injection.. [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img]