8. A bag contains four coins - Coin A, B, C, and D. Coins A and B are fair while the probability of a head from flipping coin C is 0.8 and the probability of a head from flipping coin D is 0.4. One coin is randomly selected from the bag and is used for the remainder of the game. The coin is flipped four times. a) What is the probability of getting exactly three heads? b ) What is the probability of getting exactly three heads given that the first flip is a head