In a dark room, you have a drawer containing 10 black socks and 10 white socks. What is the minimum number of socks you must pull out blindly to guarantee you have at least one matching pair of any color?
3
By the Pigeonhole Principle, if you pull 3 socks, you can have either 3 of one color, or 2 of one color and 1 of another. In any combination of 3 socks, at least two must match in color.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Easy. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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