4.设φ(x)为标准正态分布函数, _(i)= 0,A不发生, 1,A发生 (i=1,2,···,100), 且 (A)=0.8, X1,-|||-X2,···,X100相互独立,令 =sum _(i=1)^100(X)_(i), 则由中心极限定理知Y的分布函数F (y)近似于-|||-()-|||-(A)p(y) (B) circled (1)(dfrac (y-80)(4))-|||-(C) circled (1)(16y+80) (D) circled (1)(4y+80)