细心算就行了.既然问至少是多少那就是只回答对三道题的概率.
一共十种情况.0.99*0.98*0.97*0.04*0.37+0.99*0.98*0.03*0.96*0.37+0.99*0.98*0.03*0.04*0.63
+0.99*0.02*0.97*096*0.37+0.99*0.02*0.03*0.96*0.63+0.99*0.02*0.97*0.04*0.63+0.01*0.02*0.97*0.96*0.63+0.01*0.98*0.03*0.96*0.63+0.01*0.98*0.97*0.04*0.63+0.01*0.98*0.97*0.96*0.37
就是这十种情况.你自己算一下吧.太麻烦了,我就不算了.