This is a question in statistics class, and how to solve it?

(a) We toss an unfair coin showing heads (H) with probability p and tails (T) with probability 1 1). Let Y be the number of heads in n tosses. Dene random variable X in the following way: Condi- tionally on Y = y, X N exp(y) (i.e. fX|y(x) = yexp(yac), x > 0. Use the law of total probability to nd unconditional cdf FX(x) : P[X S :13]. Hint: It may be easier to derive the probability of the event {X > :13}. We use the same unfair coin as above and toss it until it shows a head. The head scores 3 and each tail scores 1. The total score is denoted Y. Find E(Y) and V(Y), and the probability we end up with a positive sore