A box contains 3 yellow, 2 red, 4 green and 3 black marbles. Two marbles are taken one after the other at random from the box. What is the probability that both marbles are red?
It should be C. There are 12 marbles total, and 2 of them are red, so 2/12 or 1/6. After the first one is drawn there are 11 marbles left 1 of which is red, so 1/11 1/11•1/6=1/66
