Suppose that there are piles of red, green, and yellow balls and that each pile contains at least 13 balls. (a) In how many ways can we select 13

Suppose that there are piles of red, green, and yellow balls and that each pile contains at least 13 balls.

(a) In how many ways can we select 13 balls?

(b) What is the probability that we select 13 balls consisting of at least one ball of each color?