You are standing in a hallway next to 3 light switches that have been switched off. There is another room down the hallway with 3 light bulbs – all are incandescent light bulbs and each light bulb is operated by one of the switches in the hallway. The door to the room is closed and you cannot see the light bulbs from the hallway. How would you figure out which switch operates which light bulb, if you can enter the room with the light bulbs only once?

What two things can you never eat before breakfast?

This puzzle has been said to have been invented by Albert Einstein as a boy and some claim that only 2% of the population can solve it.

There are 5 houses in 5 different colors. All the 5 owners are of different nationality. The 5 owners drink different beverages, smoke different brand of cigars, and own different pets. No owners have the same pet, smoke the same brand of cigar, or drink the same beverage.

1. There are five houses.
2. The Brit 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.

Who owns the zebra?