J & K CET Engineering J and K - CET Engineering Solved Paper-2004

  • question_answer
    A and B are the independent events. The probability that both occur simultaneously is \[\frac{1}{6}\]and the probability that neither occur is \[\frac{1}{3}\]The probability of occurrence of the events A and B

    A)  \[\frac{1}{2},\frac{3}{2}\]

    B)  \[\frac{1}{2},\frac{1}{3}\]

    C)  not possible    

    D)  None of these

    Correct Answer: B

    Solution :

    Given that,   \[P(A\cap B)=\frac{1}{6}\] \[\Rightarrow \] \[P(A)\,\,P(B)=\frac{1}{6}\] ?.. (i) and \[P(\bar{A}\cap \bar{B})=\frac{1}{3}\] \[\Rightarrow \] \[P(\bar{A})P(\bar{B})=\frac{1}{3}\] \[\Rightarrow \] \[(1-P(A))\,\,(1-P(B))=\frac{1}{3}\] \[\Rightarrow \] \[1-\frac{1}{3}+P(A)\,P(B)=P(A)+P(B)\] \[\Rightarrow \] \[\frac{2}{3}+\frac{1}{6}=P(A)+P(B)\] \[\Rightarrow \] \[P(A)+P(B)=\frac{5}{6}\] On solving Eqs. (i) and (ii), we get \[P(A)=\frac{1}{2},\,\,P(B)=\frac{1}{3}\] or \[P(A)=\frac{1}{3},\,\,P(B)=\frac{1}{2}\]


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