12 coins balance problem

today, in this short post I want to show you this cool puzzle that I first encountered on my summer camp. The problem goes like this:

You have got 12 coins. One of them may be false one. You can not know by looking but you have a balance weights. You are allowed to use it 3 times and find out which one of the coins is heavier or lighter (you do not know and it might happen that none is).

I really recommend you to try it out. I almost had a solution though when I checked it I saw that I had mistake in one of the scenarios. Try it out for yourself and in next post I will reveal the solution.




Try to take first step of weighting 4 coins against 4 coins, it will help you 😉


4 thoughts on “12 coins balance problem

  1. OK, I’m going to give this a go. (don’t laugh)

    Time 1: If you weigh 4 against 4 & it comes out even, then you’ve only the remaining 4. If it comes out uneven, then you’ve got the lighter 4.
    Time 2: 2 against 2. Take out the lighter 2 for the next weigh
    Time 3: 1 against 1 from the previous weigh. Lighter one is false.

    How off base am I?

    Liked by 1 person

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