Saturday, July 05, 2008

Saturday Solution: Golf Balls

Ok, so for those dying to know if they were thinking along the correct lines, here's the solution to Tuesday's Teaser.

The teaser was: "You have 9 golf balls. 8 of which are equal in weight. The ninth is slightly heavier then the rest. You also have a balancing scale. Can you use this scale two times and only two times in order to tell which ball is heavier?"

Now you know that 8 of the balls weigh exactly the same and the ninth is heavier than the rest.

So, yes you can tell which on is heavier with only two weighings.

All you have to do is separate the balls into 3 groups of 3. Place 3 balls on the left side of the scale and 3 balls on the right.

If they balance out, you know that the heavier ball is not one of those 6. If one side is heavier, you know that the heavier ball is one of those 3.

Now for your second use of the scale, place one of the remaining 3 balls on the left and one on the right. If they are equal, then it is the ball that was left out that is heavier. If either side is heavier, then that is the heavier ball.

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