A bag haves 5 white marbles and 45 blue marbles. Five balls are drawn under the situations of branch 2 (Branch 2 means repitition isn't allowed, but order doesn't matter).
A0: a sample in which there're no white marbles. N(A) =
A1: a sample in which there is exactly one white marble. N(A2) =
A2: a sample in which there are exactly three white marbles. N(A3) =