Answer
a) 3
b) 14
Work Step by Step
a) there are 2 colours so we need an integer n , such that n > 2 for socks to be of the same colour . The minimum value of n is 3. (pigeonhole principle)
b) to be sure that at least 2 socks are black he needs 14 because in the first 13 selection he may get only 1 black sock because 12 brown socks were also present in the drawer initially.
