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Post your favorite brainteasers. Throw your answer in a spoiler. If you want to comment on the answer of a brainteaser, post the first sentence of that brainteaser, then throw your answer in a spoiler. Begin:
You have nine pingpong balls. All of them are the same size, shape, color, etc., and there's no way to discern between them by touch, sight, etc.; however, one of the nine balls weighs slightly more than the other eight. The difference is so slight though, that you can't tell which ball is the heavier ball by picking the balls up or anything similar. The only thing you have that can accurately measure the difference in the one ball's weight from the other balls, is an old school balance scale (think the judge's balance, or what you used in high school science; when you put something on one side, that side will move downward and the other side will move upward. The catch here is that you're only allowed to use this scale twice to find the one ball that weighs more than the others. How do you do it?
Solution:
Post your favorites NT - works gets mad boring and it's always fun to get the mind moving again.
You have nine pingpong balls. All of them are the same size, shape, color, etc., and there's no way to discern between them by touch, sight, etc.; however, one of the nine balls weighs slightly more than the other eight. The difference is so slight though, that you can't tell which ball is the heavier ball by picking the balls up or anything similar. The only thing you have that can accurately measure the difference in the one ball's weight from the other balls, is an old school balance scale (think the judge's balance, or what you used in high school science; when you put something on one side, that side will move downward and the other side will move upward. The catch here is that you're only allowed to use this scale twice to find the one ball that weighs more than the others. How do you do it?
Solution:
In order to solve this, you first have to split the balls evenly into three groups. You add one group to each side of the scale, and you leave the third group alone. If the scale is balanced after putting the two groups of three balls on the scale, then that means the heavier ball is in the group that's not being weighed. If one side of the scale is lower than the other, then obviously the heavier ball is in that group. Once you've figured out which group the heavier ball is in, you put two balls from that group on the scale, leaving the third ball off. The same thing applies here: if the scale is balanced, then the ball that's not on the scale is the heavier ball. If one side of the scale is lower than the other side, then you know that ball is heavier.
Post your favorites NT - works gets mad boring and it's always fun to get the mind moving again.