Conditional Probability of a Marble Drawing System

Question

Suppose someone has a bag of 5 yellow, 10 red, 15 green, and 20 orange marbles. There are 4 rounds to the drawing, and each round consists of 2 steps. First, a marble is chosen at random from the bag, that color is deemed to have "won" that round. Second, all of the other marbles of the winning color are removed from the bag. (i.e. if a yellow marble is drawn in the first round, the remaining 4 yellow marbles are also removed from the bag, and round 2 begins with only the 10 red, 15 green, and 20 orange marbles in the bag). What is the probability that yellow wins the second round?

Answer 1