An urn contains 6 red, 5 blue and 2 green marbles. If 2 marbles are picked at random, what is the probability that both are red?
+591 there are 13 marbles to choose from the first time, and 12 marbles to choose from the second time, so 156 options in total, and there are 6$\cdot$5=30 ways to choose red each of those times, so 30/156=$\boxed{\frac{5}{26}}$
