Question: Urn A has four red, three blue, and two green balls. Urn B has two red, three blue, and four green balls. A ball is drawn from urn A and put into urn B, and then a ball is drawn from urn B.
a. What is the probability that a red ball is drawn from urn B?
b. If a red ball is drawn from urn B, what is the probability that a red ball was drawn from urn A?