JEE Main & Advanced Mathematics Probability Question Bank Conditional probability bayes theorem

  • question_answer
    If A and B are two independent events such that \[P\,(A)=\frac{1}{2},\,\,P(B)=\frac{1}{5},\] then

    A)                 \[P\,\left( \frac{A}{B} \right)=\frac{1}{2}\]       

    B)                 \[P\,\left( \frac{A}{A\cup B} \right)=\frac{5}{6}\]

    C)                 \[P\,\left( \frac{A\cap B}{{A}'\cup {B}'} \right)=0\]          

    D)                 All of the above

    Correct Answer: D

    Solution :

                      \[P(A/B)=P(A)\] as independent event \[=\frac{1}{2}.\]            \[P\{A/(A\cup B)\}=\frac{P[A\cap (A\cup B)]}{P(A\cup B)}\]            {Since \[A\cap (A\cup B)=A\cap [A-B-A\cap B]\]            \[=A-A\cap B-A\cap B=a\}\]            \[\Rightarrow P\left( \frac{A}{A\cup B} \right)=\frac{P(A)}{P(A\cup B)}=\frac{\frac{1}{2}}{\frac{1}{2}-\frac{1}{5}-\frac{1}{10}}=\frac{\frac{1}{2}}{\frac{6}{10}}=\frac{5}{6}\]                                 and similarly \[P\left( \frac{A\cap B}{{A}'\cup {B}'} \right)\].


You need to login to perform this action.
You will be redirected in 3 sec spinner