Скачать или смотреть The Weighing Problem

The Weighing Problem:

You have 8 identical-looking balls. One of them is slightly heavier, but you don’t know which one. You have a balance scale. What's the minimum number of weighings required te find the hewvier ball?

Solution:

You can find the heavier ball in just 2 weighings using this process:

1. Divide the 8 balls into three groups: two groups of 3 balls and one group of 2 balls.

2. Weigh the two groups of 3 balls against each other:

• If one group is heavier, the heavier ball is in that group.

• If they balance, the heavier ball is in the remaining 2 balls.

3. Now weigh any two balls from the heavier group:

• If one ball is heavier, you've found the heavier ball.

• If they balance, the heavier ball is the one you didn't weigh.