A bag has 5 red marbles, 6 blue marbles and 4 black marbles. What is the probability of a blue marble, replacing it, and then picking a black marble?

8/75

4/45

1/9

There are 15 total marbles in the bag, of which 6 are blue nd 4 are black.

The probability of pulling a blue marble from the full bag is 6/15.

The probability of pulling a black marble from the full bag is 4/15.

The probability of both events happening is

(6/15) x (4/15) = 24/225 = 8/75