【题目】-|||-12、(中等)设随机变量 sim Y(3,4) ,ϕ(x)为标准正态分布函数,则 (Xgt 2)- ()-|||-A. https:/img.zuoyebang.cc/zyb_9b9badc2472dc348f7ea003e3b018325.jpg-(1)=(2) B. https:/img.zuoyebang.cc/zyb_9b9badc2472dc348f7ea003e3b018325.jpg-varphi (dfrac (1)(2)) ...-|||-C.ϕ(2) D. varphi (dfrac (1)(2))