There are twenty coins sitting on the table, ten are heads and ten are tails. You are sitting at the table with a blindfold on. You are able to feel where the coins are, but are unable to see or feel if they heads or tails. You must now create two sets of coins. Each set must have the same number of heads and tails as the other group. You can only move or flip the coins, you are unable to determine if they are heads or tails. How do you create two even groups of coins with the same number of heads and tails in each group?
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Comments:
Anonymous - 10 years, 7 months ago
"You must now create two sets of coins." Does this require me to use all the available coins?? if not, then my two sets contain 0 coins each. If yes, then I have no better answer than using brute force; flip all 20 coins and put the first 10 into one set and 2nd to another.
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Max Burstein - 10 years, 7 months ago
You must use all 20 coins. You don't have to flip them all if you don't want to. You can choose which, if any, you want to flip.
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Max Burstein - 10 years, 7 months ago
Try writing out a few examples. I found the answer came easier that way.
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Anonymous - 10 years, 7 months ago
Separate them into two groups of 10, then flip over all the coins in one group.
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Calum - 10 years, 7 months ago
The coins will have a different coefficient of friction depending on whether the head or tail of the coin is in contact with the surface of the table. Line all the coins up and tilt the table, the coins will naturally separate. You can then divide them up equally without the knowledge that they are heads or tails just that a different side is facing up. If the coins fall off just try again but tilt for a little less time.
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James - 10 years, 7 months ago
Just flip one group of coins, if in one group you have 8 heads and 2 tails, the other group will have the reverse 8 tails and 2 heads . So flipping that group would give it the same 8 heads and 2 tails
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