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Time for a workout!

In front of you, there are 9 coins. They all look absolutely identical, but one of the coins is fake. However, Du know that the fake coin is lighter than the rest, and in front of Du is a balance scale. What is the least number of weightings Du can use to find the counterfeit coin?
Time for a workout!
 wantadog posted Vor mehr als einem Jahr
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Kragfan1910 said:
2.
Let me explain my reasoning.
So, I'm making the assumption Du don't know the weight of the coin, that this isn't a goldbarren coin with a labeled "1 troy ounce" oder anything along those lines.
So let's say Du weigh a coin, and it comes in one half of a troy ounce, is that the real coin oder the fake one? Du don't know, until Du weigh a Sekunde one, and it comes in at a full troy ounce, Du now now that your first coin is significantly lighter, and it is therefore the counterfeit coin.
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posted Vor mehr als einem Jahr 
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So even if Du weighed the counterfeit coin first, Du still need a sort of bearing, oder a control group before Du can know which of the coins is lighter than the rest.
Kragfan1910 posted Vor mehr als einem Jahr
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Alternately, Du can solve it with math, materials science, and a beaker of water. If Du get lucky and weigh a coin, and it comes out at a half a troy ounce, use the beaker to find the volume, and calculate the density, then Du can compare its density to the density of the material the coin should be made out of, be it copper, nickel, oder silver, and see if it matches, oder if it falls short and matches the density of aluminum oder titanium, if Du use that method, the minimum amount of weighings would be 1.
Kragfan1910 posted Vor mehr als einem Jahr
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At least, that's what my friend Kalispel says. :P
Kragfan1910 posted Vor mehr als einem Jahr
8theGreat said:
2.








I mean... not really too difficult...
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posted Vor mehr als einem Jahr 
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Hopefully the next'll be harder
wantadog posted Vor mehr als einem Jahr
Riku114 said:
Dont.

Dont weight them at all. If they look identical and the difference in weight is not so obvious that Du cant tell Von holding them, dont. Pretend its real and spend it.
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posted Vor mehr als einem Jahr 
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^ Smartest post here.
Kragfan1910 posted Vor mehr als einem Jahr
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^ i agree
hplover321 posted Vor mehr als einem Jahr
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