Sunday, 16 September 2012

13 coins

You are given 13 coins out of which one is defected. You don't know the defect 'heavy' or 'light'. Also you are given an authentic coin. You are allowed to use weighing balance 3 times. Give a strategy to find the defected coin and its defect.

NOTE: This is in continuation to the puzzle "Balls and Weighing Balance". If you are asked to only the defected coin, you can do so without the authentic coin also. But to find the defect, you need to figure out a new strategy making use of authentic coin.
Just, to avoid confusion, total coins would be 14(13 + 1authentic coin)