Solving puzzles just for fun - Einstein's Riddle

There is no doubt that solving puzzles is fun. We enjoy solving puzzles; we have, after-all, an innate ability for pattern-finding, for trying to find meaning in things, for problem solving and trying to find innovative solutions. Our brain releases Oxytocin when we achieve something or receive praise. There is a sense of satisfaction and the release of the hormone makes us feel good.

We’ve also been taught that doing puzzles attenuate the negative effects of age on memory and perceptual speed tasks. Interestingly there is also some research suggesting mind puzzles may not be as beneficial as we assume. For example, a study examining crosswords and aging published in the Journal of Experimental Psychology (Volume 128 [2]. 1999, pp. 131-164) found no evidence to suggest that crossword puzzle experience reduces age-related decline in cognition

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This said, and just for fun – here is an interesting puzzle to mull over. Over the years it’s had a number of different names including the zebra puzzle, and Einstein's Puzzle or Einstein's Riddle because it is said to have been invented by Albert Einstein as a boy. Many versions of the puzzle exist, including a version published in Life International magazine on December 17, 1962. It’s also suggested that only 2% of the population can solve it. Do you want to try…

Below, a list of fifteen clues is given that tell you about five houses, their inhabitants (each a different nationality), the colour their houses are painted, the beverages their inhabitants drink and also which cigarettes they smoke. From these clues you must deduce the following:

Who drinks water and where is the missing zebra? I’ve provided the solution at the end of this article.

The following version of the puzzle appeared in Life International in 1962:

1.      There are five houses.

2.      The Englishman lives in the red house.

3.      The Spaniard owns the dog.

4.      Coffee is drunk in the green house.

5.      The Ukrainian drinks tea.

6.      The green house is immediately to the right of the ivory house.

7.      The Old Gold smoker owns snails.

8.      Kools are smoked in the yellow house.

9.      Milk is drunk in the middle house.

10.   The Norwegian lives in the first house.

11.   The man who smokes Chesterfields lives in the house next to the man with the fox.

12.   Kools are smoked in the house next to the house where the horse is kept.

13.   The Lucky Strike smoker drinks orange juice.

14.   The Japanese smokes Parliaments.

15.   The Norwegian lives next to the blue house.

16.   Now, who drinks water? Who owns the zebra?

In the interest of clarity, it must be added that each of the five houses is painted a different colour, and their inhabitants are of different national extractions, own different pets, drink different beverages and smoke different brands of American cigarettes. One other thing: in statement 6, right means your right.

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).

Solution