题目20 里选 《2万]-|||-总体 approx N(2,(sigma )^2), (X1,X2···,Xn)是来自总体X的样本,X是样本均值,则 overline {X)geqslant 2} -|||-A. =dfrac (1)(4)-|||-bigcirc B. =dfrac (1)(2)-|||-C C. lt dfrac (1)(4)题目解答答案
