※ 引述《richands》之铭言： : Q46: (Lu: This question maintains a water-tight logic!) : The probability that event A will not occur is 0.8. The probability that : event B will not occur is 0.6. The probability that neither event A nor : event B will not occur is 0. What is the probability that one of the two : events of event A and event B will occur? : Answer Choices: 2/5, 3/5, 12/25 … : ANS:3/5 : Note from Lu: : From “The probability that neither event A nor event B will not occur is 0.” : → Neither A nor B will occur = 0.4 → This guarantees that “A Occurs” and : “B Occurs” are two completely separate sets that have no overlapping area. : 但CD上有人这样说 : A发生= 1 – 0.8 = 0.2 : B发生= 0.4 因为AB都不发生的状况不存在，所以AB有交集， : AB = 1/5 * 2/5 = 2/25 A非B非 = 0 : 所以1 – AB – A非B非 = 23/25 : 大家觉得是哪个呢？ ANS: 3/5 这是英文问题吧... 如果题目写neither A nor B will occur 机率=0 是 A或B都不发生的机率为0 可是请注意到他是will NOT occur → A与B一起发生的机率为0 A发生机率1-0.8 = 0.2 B发生机率1-0.6 = 0.4 两者一起发生机率0 所以两件事情中取一件发生的机率 直接相加0.2+0.4 = 0.6 = 3/5 --

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