打中一枪概率是0.9,4枪中2枪的概率
来源:百度知道 编辑:UC知道 时间:2024/05/30 05:52:49
p=0.9
4枪正好中2枪的概率
=C(4,2)p^2(1-p)^2
=[4!/(2!2!)](0.9^2)(0.1)^2
=6*0.81*0.01
=0.0486
0.9 * 0.9 * 0.1 * 0.1 * C42
=0.0081*6
=0.0486
C4(2)*9/10*9/10*1/10*1/10=273/500
C42*0.9*0.9*0.1*0.1=??
自己可以算出来了不?