P(A)=P(B)=P(C)=0.25, P(AB)=P(AC)=P(BC)=1/6
-----------------------------------------------条件不足,只能给出A,B,C都不发生的概率范围
1/6<=(1/6-P(ABC))*2+P(ABC)<=0.25
1/6<=1/3-P(ABC)<=1/4
1/12<=P(ABC)<=1/6
P(A+B+C)=P(A)+P(B)+P(C)-P(AB)-P(AC)-P(BC)+P(ABC)=3/4-1/2+P(ABC)=1/4+P(ABC)
A,B,C至少有一个发生的概率范围是: 1/3<=P(A+B+C)<=5/12
A,B,C都不发生的概率范围是: 7/12<=1-P(A+B+C)<=2/3
追问我也觉得是条件不足,因为P(ABC)不知道,可是人家说是真题
追答![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/2f738bd4b31c8701adeb83c2247f9e2f0708ffb0?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)