Riddle: A plane containing 5 people crashes into an uncharted island, and all of them survive for a limit of 5 days. 2 of them build themselves graves and die in it from the hard work. 1 person fills one of the graves with dirt and then dies next to it on day 3. The last two people build 3 graves, and put in one of the corpses, but 5 years later, 11 people are not in their graves, yet the graves are full of corpses. How?
Answer: On day four, the last two survivours(who are different sexes)found food which will last each of them 4 more years, and on the fifth day, they began reproducing. By the fourth year, ten children have been taught how to raise themselves. The children were thoughtful and put their corpses in the grave.