Einstein’s Puzzle

Thanks to Drew for pointing me to this fun logic puzzle.

Supposedly Einstein proposed this puzzle and it’s often referred to as “Einstein’s Challenge.” The question is, “Who Own’s the Fish?” And here’s the information. Go ahead and try it. And by presenting this puzzle, I am NOT advocating smoking or drinking, I merely wanted to quote the puzzle as it’s classically written.

Here’s what we know:

  1. There are five houses in five different colors.
  2. In each house lives a person of a different nationality.
  3. These five owners drink a certain beverage, smoke a certain brand of cigarette and keep a certain pet.
  4. No owners have the same pet, smoke the same brand of cigarette or drink the same drink.

Here are the clues:

  1. The Brit lives in the 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 Dunhills.
  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 Blends lives next to the one who keeps cats.
  11. The man who keeps horses lives next to the man who smokes Dunhills.
  12. The owner who smokes Bluemasters drinks beer.
  13. The German smokes Princes.
  14. The Norwegian lives next to the blue house.
  15. The man who smokes Blends has a neighbour who drinks water.

Again, the question is: WHO OWNS THE FISH?

The fact that Einstein proposed the problem is urban legend. I’m not sure why it’s named for him. Also, most sources say something like “2% of people who try this problem get it correct,” which is a completely made up statistic, as far as I know.

 I didn’t get it right, if that’s a comfort to you :-). So see if you can do better than me!

A4 Paper

I mentioned the A4 paper size (European standard) today in some of my classes and its special \sqrt{2} ratio. It has the amazing property that if you cut it in half “hamburger” style it retains the ratio. Incredible, right? Beautiful, right? Nothing special about our 8.5″ x 11″ paper, that’s for sure. For extra bonus points, give a proof of this property (it’s two or three statements–short and simple).

 

Elegantly, A0 paper is proportioned so that it has exactly 1 square meter of area. A1 is half that size, A2 half again, and so on. For more info about A4 paper, and diagrams, visit the Wikipedia page.