You have twelve coins, one of which is a counterfeit and weighs less than the legal coins. How can you use a simple balance three times to determine which coin is a counterfeit?|||You made it easy by saying that the coin is lighter.
You simply
1. put 6 coins on each side of the balance and see which side is lighter
2. take the 6 coins from the lighter side and arrange 3 on each side of the balance.
3. take the 3 coins from the lighter side once again, and put 1 coin on each side (doesn't matter which of those coins you pick)
A. if the 2 coins are the same weight, then the third one is the counterfeit
B. if one of the coins is lighter, the lighter coin is the counterfeit!
done!
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