Three marbles are randomly selected, without replacement, from a bag containing two red, three blue and four green marbles. What is the probability that one marble of each color is selected? Express your answer as a common fraction.
Choose a red one 2 out of 9 2/9
now there are 8 marbles left
choose a blue 3/8
now there are 7 left
choose a green 4/7
2/9 * 3/8 * 4/7 = ...................