Thanks to Pallav for yet another very interesting, and in this case, a classic puzzle. My 11th grade chemistry teacher, Mr. Gopinath, had given it to me, and I love this puzzle. Here it goes:
In a village of 100 people all villagers are infinitely intelligent. One day a strange disease hits the village which affects 23 people. The symptom is that if you’re affected the color of your eyes will turn yellow. The village head orders that all the villagers with disease (yellow eyes) should leave the village. The villagers meet everyday evening but they are not allowed to tell the other guy to leave. Nobody can see the color of their own eyes but moment he knows that his eyes are yellow he leaves the village. In how many days will the village become disease free.
As always, please send your answers directly to me at email@example.com. If you like the puzzle, please share it with others. If you have interesting puzzles to share, please send them to me at my e-mail given above.
Happy disease-free world!