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Billiard-balls - logic puzzle
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Nine billiard-balls are lying in front of you. Except for one they all have the same weight. The exception is a little bit heavier than the others. What is the minimal number of times you have to use a balance in order to find the wrong billiard ball? |
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Painting stairs - math puzzle
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To enter the house of the professor, you first have to walk up a stairs which consists out of twenty steps. The professor thinks his stairs are boring so he decides to paint them. He buys two colors, yellow and green. Every step will be either painted yellow or green and moreover the professor does not want to have two yellow steps directly after each other. In how many ways can the professor paint his stairs? And what is the name of the professor? |
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Sky theory - science puzzle
| Why has the sky most often a blue color? And for what reason becomes the sky becomes suddenly reddish when the sun sets? Why does this red color only appear during a sunset or sunrise and not when it is noon? |
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