posted by emma .
One of your dresser drawers contains 10 black socks and 10 blue socks. Suppose it is dark and you can’t tell what color a sock is when you look at it. If you start taking socks randomly one at a time from the drawer, how many would you have to take to guarantee that you get a pair of blue socks?
clearly you would have to draw 12, in case the first 10 were all black.