I just started physics this year, and we were assigned our first problem today. Before I continue I'd just like to stress that I am not looking for an answer. Just a hint, or something to help me out. Telling me that I'm on the right path would be helpful as well Here's the problem: -There are 12 coins, out of the 12 one is a counterfit. -11 of the coins weigh the same, the counterfit weighs either more or less than a 'normal' coin. -The only tool that may be used to solve this problem is a balencing scale, and it may be used only 3 times So far I've come up with this: Start off with 3 groups of 4 coins each. Use Scale 1 Put two groups of 4 on each side of the scale, if they balence then you know that those 8 are all 'real' coins. From here on I don't know what to do. I believe that you need to use groups of 4, but I'm not positive. What I do know is that you will need 2 procedures, 1 for if the first 2 groups balence, and one for if they don't. Is my current thinking correct?