The famous Einstein quiz: Einstein said that 98% of the people in the world cannot solve his riddle. Facts: 1: There are 5 houses in 5 different colors 2: In each house lives a person with a different nationality. 3: These 5 owners drink a certain beverage, smoke a certain brand of cigar and keep a certain pet. 4: No owners have the same pet, smoke the same brand of cigar or drink the same drink. Further Details: 1: The Brit lives in a red house. 2: The Swede keeps dogs as pets. 3: The Dane drinks tea. 4: The green house is on the immediate left of the white house. 5: The green house owner drinks coffee. 6: The person who smokes Pall Mall rears birds. 7: The owner of the yellow house smokes Dunhill. 8: The man living in the house right in the center drinks milk. 9: The Norwegian lives in the first house. 10: The man who smokes Blend lives next to the one who keeps cats. 11: The man who keeps horses lives next to the man who smokes Dunhill. 12: The owner who smokes Blue Master drinks beer. 13: The German smokes Prince. 14: The Norwegian lives next to the blue house. 15: The man who smokes Blend has a neighbor who drinks water. The question is ... WHO KEEPS FISH? If you chart out the problem, lay out each clue graphically, and slowly build a picture of which persons, drinks and pets are in which houses. Its a logical, technical and involved process. If you do all this you inevitably conclude that it is the German who must have the fish. But nowhere in the problem is even mentioned the word "fish", not in the "facts" and not in the "further details" list. So why would i want to think that when completing the map I see that German has no pet and the question is "who keeps the fish" and so the fish must be German`s. But at the same time German may have lion or duck or whatever pet. So from that I can conclude that there is no way we can say for sure that German has the fish. My friend argues that its german for sure who has the fish. Any opinions?