Well the answer is 1/3 which i cannot seem to get.Suppose that P(X=0)=1-P(X=1). If E[X]=3Var(X), nd P(X=0).
I calculate P(X = 1) = p
thus P(X = 0) = 1 - p
Var(x) = (1 - p)/p^2
E(x) = 1 / p
Solving this u get
p = 3(1 - p) and thus p = 3/4...so P(x = 0) = 1/4 and not 1/3 which is the answer.
Any help would be appreciated.
Thank-you