A bag contains 4 red marbles, 5 yellow marbles, and 6 blue marbles. Three marbles are to be picked out randomly (without replacement). What is the probability that exactly two of them have the same color?
\(p = \dfrac{\dbinom{4}{2}\dbinom{11}{1}+\dbinom{5}{2}\dbinom{10}{1}+\dbinom{6}{2}\dbinom{9}{1}}{\dbinom{15}{3}}\)
