RE: The 12 Coins Puzzle
January 27, 2010 at 6:31 am
(This post was last modified: January 27, 2010 at 6:42 am by Ephrium.)
Mine is the answer. I did not post the other easy options.
I do not know why you cannot get it but, I post a simplified version. I took out replacing the coins since it did not matter. You have coins ABCDEFGHIJKL
Algorithm:
1.Weight ABCD vs EFGH. If unbalanced, go to 2. If balanced, go to 5.
2.Weight ABH vs ECD. If it is now balanced, the odd coin must be in FG which you have taken out. If the scales switch, it must be in CDH. If it remains, it must be in ABE.
3. Whether it is in ABE or CDH, Use Two coins in the same side and same group against each other. For instance, If ABH AND ABCD Had been heavier from the start, (As concluded, the Odd coin must be in ABE) use B against A. The heavier coin is the odd one out. If balanced, it is E which is the odd one
5. If ABCD vs EFGH were balanced, weight ABC vs IJK. Say IJK is heavier , go to 6.
6. Weigh I vs J. The heavier coin is the one. If not , the odd coin is K.
As I have said, my method can do it for 13 Coins. High IQ is it not.
Some simple cases I have left out, such as if two coins were left, weigh any coins which you are sure of against one of them.
Question any weighting combination and out come you are not sure, Etc. ABCD heavier in step 1, Then ABH was lighter than ECD, Then The last weighting of C vs D was equal. It shows H was the lighter coin.
I do not know why you cannot get it but, I post a simplified version. I took out replacing the coins since it did not matter. You have coins ABCDEFGHIJKL
Algorithm:
1.Weight ABCD vs EFGH. If unbalanced, go to 2. If balanced, go to 5.
2.Weight ABH vs ECD. If it is now balanced, the odd coin must be in FG which you have taken out. If the scales switch, it must be in CDH. If it remains, it must be in ABE.
3. Whether it is in ABE or CDH, Use Two coins in the same side and same group against each other. For instance, If ABH AND ABCD Had been heavier from the start, (As concluded, the Odd coin must be in ABE) use B against A. The heavier coin is the odd one out. If balanced, it is E which is the odd one
5. If ABCD vs EFGH were balanced, weight ABC vs IJK. Say IJK is heavier , go to 6.
6. Weigh I vs J. The heavier coin is the one. If not , the odd coin is K.
As I have said, my method can do it for 13 Coins. High IQ is it not.
Some simple cases I have left out, such as if two coins were left, weigh any coins which you are sure of against one of them.
Question any weighting combination and out come you are not sure, Etc. ABCD heavier in step 1, Then ABH was lighter than ECD, Then The last weighting of C vs D was equal. It shows H was the lighter coin.
