who drinks the water and who owns the zebra
Zebra Puzzle Assuming that one person drinks water and one owns a zebra, then it is possible not only to deduce the answers to the two questions, but to figure out a complete solution of who lives where, in what color house, keeping what pet, drinking what drink, and smoking what brand of cigarettes. By considering the clues a few at a time, it is possible to slowly build inferences that incrementally complete the puzzle's unique correct solution. For example, by clue 10, the Norwegian lives in house #1, and by clue 15, house #2 must be blue. The Norwegian's house therefore cannot be blue, nor can it be red, where the Englishman lives (clue 2), or green or ivory, which are next to each other (clue 6). It must therefore be yellow, which means the Norwegian also smokes Kools (clue 8).