Achef needs to make 8 servings of fruit salad. he has 2 1/2 pounds of fruit salad. how much fruit salad will be in each serving?

There are three bags: a (contains 2 white and 4 red balls), b (8 white, 4 red) and c (1 white 3 red). you select one ball at random from each bag, observe that exactly two are white, but forget which ball came from which bag. what is the probability that you selected a white ball from bag a?