Statistics And Probability Question 335

Question: The probability of happening at least one of the events A and B is 0.6. If the events A and B happens simultaneously with the probability 0.2, then $ P,(\bar{A})+P,(\bar{B})= $

[Roorkee 1989; IIT 1987; MP PET 1997; DCE 2001; J & K 2005]

Options:

A) 0.4

B) 0.8

C) 1.2

D) 1.4

Show Answer

Answer:

Correct Answer: C

Solution:

  •                 We are given that                                                                                          $ P(A\cup B)=0.6 $   and                                                                                          $ P(A\cap B)=0.2 $  .                    We know that if                                                                                                      $ A $   and                                                                                                      $ B $   are any two events, then                                                                                                                                                 $ P(A\cup B)=P(A)+P(B)-P(A\cap B) $                                                                                                                                               $ 0.6=1-P(\bar{A})+1-P(\bar{B})-0.2 $                                                                                                                           
    

$ \Rightarrow P(\bar{A})+P(\bar{B})=2-0.8=1.2 $ .