Question

两两独立的3个随机时间A,B,C,满足ABC＝空集,且P（A）＝P（B）＝P (C )=X,求P（A＋B＋C）＝0.75

Answer 1

P(AB)=P(AC)=P(BC)=X^2,

P(A+B+C)=P(A)+P(B)+P(C)-P(AB)-P(AC)-P(BC)+P(ABC)

=X+X+X-X^2-X^2-X^2+0=3X-3X^2=0.75

解得：X=0.5