Imagine you have 12 billiard balls
and . All of them are of the same weight except one.
Decide which ball that is not of the same weight as the
others, and decide whether it should be heavier or lighter than the other balls.
I am now going to determine which ball is different from the others and whether it is heavier or lighter.
I am going to do this by using a balance scale not more than 3 times.
When you have decided which ball is different and in which way it is different (heavier or lighter) then