\\l \\ '1 I \\'kl 13. A box has 10 red balls, 10 green balls, 10 blue balls and 10 yellow balls. Each set of 10 balls is numbered 1 to 10. Suppose four balls are chosen from the box. (a) How many ways can there be four of the same colour? (b) How many ways can there be three of one colour and one of another colour? (c) How many ways can there be two of one colour and two of a different colour