Answer:

Step-by-step explanation:
GIVEN: A bag contain
red marbles,
green marbles and
blue marble. A marble is chosen at random from the bag and not replaced, then a second marble is chose.
TO FIND: What is the probability both marbles are green.
SOLUTION:
Total marbles in bag 
total number of green marbles 
Probability that first marble will be green 

Probability that second marble will be green 

As both events are disjoint
probability both marbles are green 

Hence the probability both marbles are green is 