A bag contains 2 black marbles, 2 orange marbles, 2 red marbles, and 5 blue marbles. If 2 marbles are selected, what is the probability of picking 2 black marbles?

There are LaTeX: \displaystyle C(11,2)=55 to select 2 marbles. There are LaTeX: \displaystyle 1 ways to select 2 black from 2 black. This gives the probability LaTeX: \displaystyle \frac{1}{55}