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# How is it possible?

There are eight ping pong balls. One is lighter than the others, which all weigh the same. How is it possible to tell which is the lightest ball by using a balance scale only twice?

Place three balls on one side of the scale and three on the other. If the two sides balance, then the light ball is among the remaining two and a second weighing will tell which it is. If the first weighing shows a disparity, however, take the three balls weighing the least and place one on each side of the scale, putting one to the side. If the two balance, the third is the light one. If they dont balance, you know which one is light.

## 3 words

Though small I am, yet, when entire,I've force to set the world on fire.Take off a letter, and 'tis clearMy punch will hold a herd of deer:Dismiss another, and you'll findI once contained all humankind.Spark, park, arkmore...

## Why?

A woman lives in a skyscraper thirty-six floors high and served by several elevators which stop at each floor going up and down. Each morning she leaves her apartment and goes to one of the elevators. Whichever one she takes is three times more likely to be going up...