1. Urn 1 contains 5 red, 4 white, and 6 blue marbles. Urn 2 contains 12, red, 2 white, and 3 blue marbles. One urn is chosen at random and then one marble is drawn at random from that urn. Find the probability that
(a) a red marble is drawn
(b) a red marble is drawn, given that Urn 2 was chosen
2. Roll a pair of dice. Find the probability that the sum is odd, given that one of the dice is odd.