Here is 1 red marble, 2 green marbles, and 5 blue marbles. you draw two marbles from the urn, but replace the first marble before drawing the second. find the probability that the first mable is blue and the second is green.

Total number of Marbles = 1 + 2 + 5 = 8
P(R) = 1/8
P(G) = 2/8 = 1/4
P(B) = 5/8
R = Event of picking a red marble
G = Event of picking a green marble
B = Event of picking a blue marble
The events are independent, i.e. the outcome of one trial will not affect the probabilities of the outcomes for another trial.
So, we can just multiply the P(B) by P(G) to find the desired overall outcome of the compound events:
5/8 * 1/4 = 5/32