Three urns of the same appearance are given as follows: Urn A contains 5 red and 7 white balls. Urn B contains 4 red and 3 white balls. Urn C contains 3 red and 4 white balls. An urn is selected at random and ball is drawn from the urn. (1) What is the probability that the ball drawn is red. (2) If the ball drawn is red, what is the probability that it came from urn A.​