In a drawer, there are 10 matching black socks, 10 matching white socks, and 10 matching red socks. The room is pitch black. What is the minimum number of socks you must pull out to guarantee you have at least one complete matching pair of any color?
Four socks.
With 3 possible colors, pulling 4 socks ensures by the Pigeonhole Principle that at least two socks will share the same color, forming a pair.
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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