There are 9 identical balls but only one of them has a higher weight. You are also given a weight balance. How many attempts would you require to identify the ball with the extra weight and how?
Classic puzzle, you need
You do this by
Measuring a set of three versus a set of three. The set with the heavy ball is identified. (The heavier set on the scale, or, if they are equal, the set not on the scale)
Weigh two of the balls in said set of three, same thought process. Heavier on the scale, or the one left over if they are the same.