Probability

This is what I still remember:

5c1*1c1*4c1/12c3

12 is the sum of the marbles

5 over 12 x 1 over 11 x 4 over 10= 1 OVER 66 (1/66)

the probability to draw:

black marble: 5/12

green: 1/12

$black, green, black \\ \frac{5}{12} \times \frac{1 }{12 (-1) \text{ because you draw one marble)}} \times \frac{5(-1) \text{ because you draw one black marble)}}{12(-2) \text{ because you draw two marbles)}} \\ (5/12)*(1/11)*(4/10)=1/66$