Suppose you choose two marbles from a bag containing 2 red marbles, 5 white marbles, and 3 blue marbles. find the probability that both marbles are blue. find p(red than blue)

2r + 5w +3b = 10 - marbles altogether.

1)  P(1st marble blue) =3/10
After 2 blue marbles and 9 marbles altogether left.
 P(2nd marble blue) =2/9.
P(both marbles blue) = 3/10*2/9=2/30

2) P(1st marble is red) = 2/10=1/5
Now, we have 3 blue marbles and 9 marbles altogether.
P(2nd marble is blue) = 3/9=1/3
P(red then blue)= 1/5*1/3=1/15