A bricklayer has 9 bricks. 8 bricks weigh the same amount, but one brick is slightly heavier than the rest. The bricklayer wants to find the heavy brick. He has a balance scale. How can he find the heavy brick in only two weighings?
Answer
He should divide the bricks into 3 groups of 3. He then weighs 2 sets of 3 bricks against one another. If they balance, the heavy brick is in the group that was set aside. If they do not balance, he then takes the group that was heaviest. He has 3 bricks left. He takes the 2 bricks from the 3 and weighs them against each other. If they balance, the heavy brick is the one which is set aside. If they do not balance, the scale will show which is the heavier brick.
