• I would build 4 blocks of 3 balls A,B,C,D
    1. weigh:  let us compare the first two blocks, A and B
    two cases arise: A=B, AB
       a) If A=B we know that the odd block is either C or D
            2a) weigh take A&C, if they are equal the odd ball is in D, if not then it is C
            3a) weigh take two balls from D/C to determine the odd ball
    b) cas…[Read more]