一铸件上无缺陷的概率=P(0,0.5)=e^(-0.5)=0.60656仅有1个缺陷的概率=P(1,0.5)=0.5*e^(-0.5)=0.3033有多于1个缺陷的概率=1-P(0,0.5)-P(1,0.5)=0.0914
1/10和9/10
