Question

电路由电池A与两个并联的电池B,C,串联而成,设电池A,B,C相互独立,且它们损坏的概率依次为0.3,0.2 0.2 ,

Answer 1

A 串(B并C)

损坏率=P(A坏 或 (BC都坏))

=P(A坏)+P(BC都坏)-P(ABC都坏)

=0.3+(0.2*0.2)-(0.3*0.2*0.2)

=0.3+0.04-0.012

=0.34-0.012

=0.328

或由电路好的概率下手

A好且(B或C好)

=A好*(1-BC都坏)

=0.7*(1-0.04)

=0.672

电路坏的概率

1-0.672

=0.328