Statistics And Probability Question 290

Question: If A and B are any two events, then the probability that exactly one of them occur is

[BIT Ranchi 1990; IIT 1984; RPET 1995, 2002; MP PET 2004]

Options:

A) $ P,(A)+P,(B)-P,(A\cap B) $

B) $ P,(A)+P,(B)-2P,(A\cap B) $

C) $ P,(A)+P,(B)-P,(A\cup B) $

D) $ P,(A)+P,(B)-2P,(A\cup B) $

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Answer:

Correct Answer: B

Solution:

  •                 Required probability                                                                                                     $ =A $   occurs and                                                                                                      $ B $   does not occur or B occurs and                                                                                                      $ A $   does not occur                                                                                                                                             $ =P(A\cap \bar{B})+P(\bar{A}\cap B) $                                                                                                                                                 $ =P(A)-P(A\cap B)+P(B)-P(A\cap B) $                                                                                                                                                                 $ =P(A)+P(B)-2P(A\cap B) $ .