When you put your christmas tree in the attic, you find an old set poolballen where eight balls of remaining. The balls feel identical to, but you know that one ball is slightly heavier than the rest. the
On your attic you will also find an antique scale with two arms. You're pretty sure that the thing is broken if you do it more than twice.
you Can discover what ball is slightly heavier than the rest by the scale, but twice ?