Question

3. A drawer contains several loose socks, each sock is only blue or black. You have to grab

socks out of the drawer in the dark, so as not to wake your partner. What is the minimum
number of socks you must pull out to be sure you have two of the same color?

Answer 1

Answer: 3 socks

Reason:

You could get lucky to pull out 2 blue socks or 2 black socks in a row. But you could also get unlucky to have 1 blue + 1 black, or the other way around.

That third sock selected will guarantee you picked at least 2 of the same color. This is simply because there aren't any other colors left to pick from.

For more information, check out the Pigeonhole Principle.