Einstein wrote this quiz last century. He said that 98% of the people in the world cannot solve the quiz.

• There are 5 houses in 5 different colors
• In each house lives a person with a different nationality
• These 5 owners drink a certain type of beverage, smoke a certain brand of cigar, and keep a certain pet
• No owners have the same pet, smoke the same brand of cigar or drink the same drink.

The answer: The German is the only one without a pet, therefore he must be the one who owns the fish.
If you got it right you are one of the 2% who can. Congratulations.

Norwegian	Dane	Brit	German	Swede
Yellow	Blue	Red	Green	White
Water	Tea	Milk	Coffee	Beer
Dunhill	Blend	Pall Mall	Prince	Blue Master
Cats	Horses	Birds	[ Fish ]	Dogs

I solved it in around 20 minutes, although I didn't time it officially. Here are my notes as I solved it (I made one slip with the Beer and Blue Master, but ultimately realized that it had to be the owner of the White house and not the Blue) and the final cleanup.