You have 15 blue socks and 20 green socks in a drawer. How many socks must you take from the drawer (without looking) to be sure of getting:

Question

a.three socks of the same color?

b. two socks with different colors?

Answer 1

a.)  5 (if the first 4 you draw are 2 blue and 2 green then you must draw a 3rd of one of the colors on the fifth draw) 

 

b.)  21 (if the first 20 you draw are all green you must get a blue one on the 21st draw)