In: Statistics and Probability
Three boxes, one large, one medium, and one small, contain white and red balls. The large box, which is chosen half the time, contains fifteen white balls and eight red ones; the medium box, which is chosen three times out of ten, contains nine white balls and three red ones. The small box contains four white balls and five red ones. (a) On choosing two balls at random from the large box, what is the probability of (i) getting two white balls? (ii) getting one white and one red ball? (b) After selecting one of the boxes according to the prescribed probabilities, what is the probability of getting one white and one red ball from this box? (c) Given that a box is chosen according to the prescribed probabilities, and that a white ball is randomly picked from that box, what is the probability that the ball was actually chosen from the large box?