The probability that both be green if you don’t replace the marble after the first pick?

Question

A box contains seven green marbles, six blue marbles and eight orange marbles. Without looking, you choose two marbles out of the bag. What is the probability that both be green if you don’t replace the marble after the first pick? 

0.33

0.10

0.11

0.67

Answer 1

There are 21 marbles. The probability of picking 2 green ones without replacement is

(7/21)*(6/20) = .10