Answer:
2/25
Explanation:
So 30 total marbles.
The marble is being REPLACED this time. Our denominator (30) won't change for this example because we're putting the marble back in the bag in between selections.
Prob (blue) = 12/30
We put that marble back so we still have 30 marbles in the bag.
Now we're going to look for prob(black) = 6/30
Multiply these 2 'events' by each other; they are independent events.
(12/30) x (6/30) = 2/25