Suppose that we have two identical boxes: box 1 and box 2. box 1 contains 5 red balls and 3 blue balls. box 2 contains 2 red bal
ls and 4 blue balls. a box is selected at random and exactly one ball is drawn from the box. (a) what is the probability that the ball is blue? (b) given that a selected ball is blue, what is the probability that it came from the rst box?
(a) The probability of drawing a blue marble at random from a given box is the number of blue marbles divided by the total number of marbles. We assume that the probability of selecting one of two boxes at random is 1/2 for each box.