Answer:
the probabilities are just
6/13 * 5/12 for two black marbles
6/13 * 7/12 for a black marble first, white second
7/13 * 6/12 for a white marble first, black second
7/13 * 6/12 for two white marbles
the 13 is just the summ of all marbles and the 12 is when we alrdy took one out of the bag. 5, 6 and 7 are the current numbers of marbles of some color respectively
