Assume we flip a strange coin with k Pr(Tail) = Pr(Head) = k+1 on the kth flip, k = 1, 2, ... k+1 Let X be the number of flips of this coin until the first tail is observed. Assuming the coin flips are independent, (a) Find the probability mass function of X. (b) Find the mean E(X) and variance Var(X). Hint: You can use this result without proof: OO E = e. k! k=0