三个都是白:P=0.25*0.25*0.25
一红二百:P=0.75*0.25*0.25+0.25*0.75*0.25+0.25*0.25*0.75=0.75*0.25*0.25*3
一白两红:P=0.25*0.75*0.75*3
三个袋子都抽到白球的概率是
0.25³=1/64
1红2白的概率是
C(3,1)0.75×0.25²=9/64
2红1白的概率是
C(3,2)0.75²×0.25=27/64
1红2白的概率是C(3,1) 0.75×0.25²=9/64, 2红1白的概率是C(3,2) 0.75²×0.25=27/64