1. We have two urns. The first urn contains three balls labeled 1, 2, and 3. The second urn contains four balls labeled 4, 5, 6, and 7. We choose one of the urns at random (with equal probability) and then sample one ball (uniformly at random) from the chosen urn. (a) What is the probability that we picked the ball labeled 5? (b) What is the probability that the first urn was chosen, given that we picked an odd-numbered ball