Pair of Socks puzzle: You have 100 black socks and 100 white socks mixed up in a drawer. You must pick socks blindly from the drawer. How many socks you need to take out to be sure of having a matching pair?
Note that question does not ask for specific color socks but just a matching pair. It can be of white or black color either.
Answer: 3 socks
3 socks we need to pull out to make sure we are getting a matching pair of socks either black or white.
See the combination below if we take out 3 socks from drawer blindly.
WBB
WWB
WWW
BWW
BBW
BBB
Note that every attempt contains a pair of socks either Black or White. So, if we pick 3 socks from drawer then we must get a pair of either color black or white.