Just because you love it when I post mathematical puzzles, and also because I got two books packed full of them for Xmas 
Here is the problem:
You have 12 coins, each one indistinguishable from the other in terms of size and appearance, and all but one of them weighing the same. That is to say, 11 of them have the same weight, whilst one of them is either lighter or heavier than the rest.
You also have a pair of scales that measures accurately. Your quest is to find which coin is the oddly weighted one, and to determine whether it is heavier or lighter than the rest of the coins.
Here is the catch (and the puzzle):
You are only allowed to use the scales, and are only allowed 3 measurements in order to solve the puzzle.
By three measurements, I mean putting X number of coins on one side of the scales, and Y number on the other, and seeing whether the scales tilt to one side, or remain balanced. What groupings you put the coins into to measure them is totally up to you (so you could measure 11 coins against 1...but I wouldn't!), but after you have recorded three measurements, you have to reveal which coin has a different weight and whether that coin is heavier or lighter than the others.
Good luck
Here is the problem:
You have 12 coins, each one indistinguishable from the other in terms of size and appearance, and all but one of them weighing the same. That is to say, 11 of them have the same weight, whilst one of them is either lighter or heavier than the rest.
You also have a pair of scales that measures accurately. Your quest is to find which coin is the oddly weighted one, and to determine whether it is heavier or lighter than the rest of the coins.
Here is the catch (and the puzzle):
You are only allowed to use the scales, and are only allowed 3 measurements in order to solve the puzzle.
By three measurements, I mean putting X number of coins on one side of the scales, and Y number on the other, and seeing whether the scales tilt to one side, or remain balanced. What groupings you put the coins into to measure them is totally up to you (so you could measure 11 coins against 1...but I wouldn't!), but after you have recorded three measurements, you have to reveal which coin has a different weight and whether that coin is heavier or lighter than the others.
Good luck
