three urn are given , each containing red and black ball as indicated below: Urn I: 6 red and 4 black balls. Urn II : 2 red and 6 black balls. Urn III:1 red and 8 black balls. An urn is choosen at random and a ball is drawn from that urn.the ball drawn is red.find the probability that the ball is drawn either from urn II or from urn III.
