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A counterfeit coin 
20070305 

From Delian: Hi there, I have a counterfeit penny problem  however this one is slightly more challenging. I have twelve pennies, and one of them is counterfeit. The only difference between the counterfeit coin and the real ones is that the counterfeit is EITHER heavier or lighter than the others (We don't know which). I need to be able to solve this in only three weightings, and I REALLY NEED HELP!!! Answered by Penny Nom. 


