(Final Problem of the school year 2007-2008)
Howie is leaving for a trip at 3:00 A.M. At the last minute he remembers that he forgot to pack one pair of white socks and one pair of black socks for his trip. In order not to wake his brother, who shares the same room with him, he decides not to turn on the light in the room (and therefore, he cannot see anything) and simply reach into the sock drawer and take as many socks as he needs with him. The drawer contains 12 identical individual white socks, 9 identical individual black socks, and 8 individual Halloween socks, all mixed together. What is the least number of socks he must take with him to guarantee that he has a pair of white socks and a pair of black socks? An answer must be accompanied by an explanation.
(Due June 13, 2008)
