There is a large tray with red, blue and green marbles in it. In fact, there are 20 red marbles, 30 blue marbles and 40 green marbles. In that tray, the marbles are continuously moving around in Brownian (random) motion – often hitting each other.

If two marbles of same color hit each other, they just bounce off and continue. However, if two marbles of different color hit each other, then, both change to the third color and then bounce off and continue. All such hits are always between two marbles only. (no simultaneous three or more marbles hitting each other).

So a red and blue marble hitting each other will make both of them turn green and so on….

Is it ever possible for all the marbles in the tray to become of one color? If so, which color will it be?