题目19.7设 sim N(0,1),-|||-(1)求 X=0 , Xleqslant -1.25 |X|gt 0.68 ;-|||-(2)求λ,使它满足 Xgt lambda =0.05 ;-|||-(3)求λ,使它满足 2Xleqslant lambda =dfrac (1)(3).题目解答答案