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minority505
New Member
Joined: 24 Nov 2006
Posts: 5
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 Posted: Fri Nov 24, 2006 7:05 am Post subject: Fake Coins |
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you have ten stacks of ten gold coins, and one of the stacks is fake. the one and only way to tell the difference between a gold coin and a fake coin is a real coin weighs 1.0 grams and a fake coin weighs exactly 0.1 gram less. you have a electronic scale in front of you. you can put on any coins you like, but when you press the "weigh" button, it will tell you the weight and then go dead. basically, you can only use the scale once. no taking coins on and off.
so.
in order to spend these lovely coins, you have to figure out which stack is fake, as to avoid being arrested. and no, you cant take it to the treasury. thats cheating. think logic.
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Vertabladehot2m
Guy Who Comes A Lot
Joined: 10 Nov 2006
Posts: 190
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| Posted: Sat Nov 25, 2006 5:42 am Post subject: off the top of my head.. |
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| umm.. you lift each of the stacks once and determine which of stacks is less heavy?
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minority505
New Member
Joined: 24 Nov 2006
Posts: 5
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| Posted: Sat Nov 25, 2006 8:15 pm Post subject: |
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sorry, but thats wrong.
grams arent so detectable with the naked eye.
or hand in this case.
you need to use the scale.
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Blaze
Site Regular
Joined: 20 May 2006
Posts: 73
Location: In Australia!!!... Go Australa!!!!
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| Posted: Wed Nov 29, 2006 6:39 am Post subject: |
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| Well, if you think about. One whole stack is only going to be as heavy as 1 real coin so it would be pretty detectable. And does the scale compare seperate weights or does it just weigh one whole mass?
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some-g
Site Admin
Joined: 14 Mar 2005
Posts: 189
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| Posted: Wed Nov 29, 2006 9:51 am Post subject: answer to weighing fake coins |
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Onto the scale place 1 of the coins from the first stack, two from the second stack and so on, finishing with putting all 10 coins from the 10th stack on the scale.
The weight will be between 54 grams and 54.9 grams, reduced .1 grams for every fake coin on the scale.
so, if the weight is:
54.9 the first row is fake,
54.8 the second row is fake,
54.7 the third row is fake,
54.6 the fourth row is fake,
54.5 the fifth row is fake,
54.4 the sixth row is fake,
54.3 the seventh row is fake,
54.2 the eighth row is fake,
54.1 the ninth row is fake,
54 grams exactly? The fake coins are in row 10
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theintellectual
Site Regular
Joined: 26 Oct 2006
Posts: 55
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| Posted: Wed Dec 06, 2006 11:41 pm Post subject: |
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| I like some-g's answer.
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deryk
Guy Who Comes A Lot
Joined: 19 May 2006
Posts: 159
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| Posted: Wed Dec 20, 2006 11:57 pm Post subject: |
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| blaze and some g answers would both work imho
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theintellectual
Site Regular
Joined: 26 Oct 2006
Posts: 55
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| Posted: Sat Dec 23, 2006 11:41 pm Post subject: |
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| No, blaze's answer wouldn't make sense, it said a fake coin weighed .1 gram LESS than a real coin, not 1 fake coin weighed .1 gram.
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deryk
Guy Who Comes A Lot
Joined: 19 May 2006
Posts: 159
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| Posted: Sun Dec 24, 2006 12:06 am Post subject: |
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| bleh yeah i misread
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