A box contains 20 red marbles and 30 blue marbles. a second box contains 10 white marbles and 40 black marbles. if you choose one marble from each box without looking, what is the probability that you get a blue marble and a black marble?

To determine the probability that you get a blue marble and a black marble, let Event A = the probability to get a blue marble; and Event B = the probability to get a black marble.

Events A and B are independent, that's why the probability that they will both occur is:P (A and B) = P (A) x P (B)

P (A) = 30/50P (B) = 40/50

P (A and B) = (30/50) (40/50) P (A and B) = 1200/2500

P (A and B) = 0.48 or 48%

The probability that you get a blue and black marble is 48%.