I like this problem.Originally Posted bymalaygoel

Becuase there are two boxes we know one of them contains at least 33 balls. 33 divided by 4 is 8 with a remainder of 1, so we know there are at least 9 of one color balls in one box. There are at most 4 different sizes of balls, so 9 divided by 4 is 2 with a remainder of 1. Therefore, there are at least 3 balls which lie in the same box, have the same colour, and the same size.