alphazc 发表于 2012-2-26 13:12 
i think should be normal approximation too. Claims frequency follows poisson, E(N)=V(N)=5. Severity ...
juz noticed, V(S)=E(N)V(X)+E(X square)V(N) is wrong...
should be V(S)=E(N)*V(X)+E(X)^2*V(N)
you might want to check ur study manual again