A bag contains 4 blue marbles, 3 orange marbles, 4 pink marbles, and 2 green marbles. If 4 marbles are selected, what is the probability of picking 4 blue marbles?

There are LaTeX: \displaystyle C(13,4)=715 to select 4 marbles. There are LaTeX: \displaystyle 1 ways to select 4 blue from 4 blue. This gives the probability LaTeX: \displaystyle \frac{1}{715}