Statistics And Probability Question 534

Question: $ P(A\cup B)=P(A\cap B) $ if and only if the relation between $ P(A) $ and $ P(B) $ is

[IIT 1985]

Options:

A) $ P(A)=P(\bar{A}) $

B) $ P,(A\cap B)=P(A’\cap B’) $

C) $ P,(A)=P,(B) $

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

  •                  $ P(A)=P(B) $                     As this gives  $ P(A\cup B)=P(A)+P(B)-P(A\cap B) $                                  or  $ P(A)=2P(A)-P(A) $  
    

$ \Rightarrow P(A\cup B)=P(A\cap B). $