A drawer contains 10 black socks and 10 white socks mixed together in total darkness. What is the minimum number of socks you must pull out to guarantee you have at least one matching pair of any color?
3 socks
Using the pigeonhole principle, if you pull out 3 socks, you can have at most two different colors represented (black and white). Therefore, at least two of the three socks must share the same color, guaranteeing a matching 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.
More logic riddles
A merchant has two hourglasses: a 7-minute glass and an 11-minute glass. He needs to time exactly 15 minutes to boil an egg, with no extra measuring tools. How can he do this?
A collector has a shelf of ancient coins. Half of the coins are gold, a quarter are silver, a sixth are bronze, and the remaining 3 are copper. How many total coins are on the shelf?
A row goes: basket, basket, carrot, basket, basket, carrot, basket, basket. What comes next?
A row goes: dinner roll, dinner roll, corn cob, dinner roll, dinner roll, corn cob, dinner roll, dinner roll. What comes next?
I am a bunch of flowers wrapped in paper and given to someone special. What am I?
I am a three-digit number. My tens digit is twice my hundreds digit, and my ones digit is three times my hundreds digit. If the sum of all my digits is 12, what number am I?