Solution to the Odd Ball Out problem

thescienceofdeductionandmore:

To remind you, here’s the question:

You have 8 identical-looking balls.  7 of them weigh the same, and one of them weighs slightly more.  Using a balance-type scale, how can you determine the heavier ball with only two weighings?

Solution:

1. Weigh 3 against 3.

2. If they are equal, you know the heavier ball is among the remaining 2, so weigh them against each other to identify the heavy ball.

3. If one set of 3 is heavier, you know the heavier ball is among those 3.  So choose 2 of them and weigh them against each other.  If one is heavier, that is the heavier ball.  If they are equal, the one you didn’t weigh is the heavier ball.

September 01, 2018 at 11:21PM