: You're a bus driver. At the first stop 4 people get on. At the second stop 8 people get on, at the third stop 2 people get off and, at the forth stop everyone got off. The question is what color are the bus driver's eyes?
My eye colour, which is brown. This is a kind of brain teaser. A brain teaser is a form of puzzle that requires thought to solve. It often requires thinking in unconventional ways with given constraints in mind; sometimes it also involves lateral thinking. Logic puzzles and riddles are specific types of brain teasers.
Q: If three hens lay three eggs in three days, how many eggs does a (statistical) hen lay in one day?
A1: One third. (Note: 3 hens = 3 eggs / 3 days → 3 hens = (3 / 3) (eggs / days) → 1 hen = (1 / 3) (egg / days))
A2: Zero or one (it's hard to lay a third of an egg).