A bag contains 6 blue marbles, 5 white marbles, and 4 red marbles. If three marbles are randomly selected from the bag, what is the probability that the marbles selected will be of the same color? Express your answer as a common fraction.
The probability you draw all blue is 6/15 * 5/14 * 4/13= 120/2730
all white: 5/15 * 4/14 * 3/13= 60/2730
all red: 4/15 * 3/14 * 2/13= 24/2730
add them together to get probability of any one of them happening: (120+60+24)/2730
=204/2730
=34/455
