Hi all, i am trying to understand branching processes but struggling.... on this question for instance....

Consider a branching process in which the distribution of the number of offspring of a single individual is given by:

P(Za = 0) = 0.25, P(Za = 1) = 0.5 and P(Za = 2) = 0.25

What is the distribution of X2?

What is E(X2)?

What is Var(X2)?

Thank you