Question

一立方米水里有两个小虫,现取0.1立方米水,问有小虫的概率是多少

Answer 1

几何概型

有小虫的概率是:1-C(2,0)*(1-0.1)*(1-0.1)=1-0.9*0.9=1-0.81=0.19

换一种算法:C(2,1)*0.1*(1-0.1)+C(2,2)*0.1*0.1=2*0.1*0.9+1*0.1*0.1=0.18+0.01=0.19