A bag contains 4 white and 5 black balls . Another bag contains 5 white and 7 black balls . A ball is transferred from the first bag to the second and then a ball is drawn from the second bag . Find the probability that the ball drawn is white.

1 answer

P(white transferred,white drawn) = 4/9 * 6/13
P(black transferred, white drawn) = 5/9 * 5/13
so, P(white drawn) = (4*6 + 5*5)/(9*13) = 49/117