could you check the first question again!
2. Two coins are flipped. One is fair with head on one side and tail on other. The second coin is tricky one - it has 2 tails on both sides. She picks one at random and flips it.
(a) Probability it lands heads up?
(1/2)*(1/2) = 1/4
(b)it lands tails up, probability she picked up fair coin?
(1/2)/(3/4) = 2/3