JEE Main & Advanced JEE Main Paper Phase-I (Held on 08-1-2020 Morning)

  • question_answer
    Let A and B be two independent events such that \[P(A)=\frac{1}{3}\] and \[P(B)=\frac{1}{6}.\] Then, which of the following is TRUE? [JEE MAIN Held On 08-01-2020 Morning]

    A) \[P(A/B)=\frac{2}{3}\]  

    B) \[P(A'/B')=\frac{1}{3}\]

    C) \[P(A/B')=\frac{1}{3}\]

    D) \[P(A/(A\cup B))=\frac{1}{4}\]

    Correct Answer: C

    Solution :

    [c] For option (1) \[P(A/B)=\frac{P(A\cap B)}{P(B)}=P(A)=\frac{1}{3}\] Similarly \[P(A'/B')=P(A')=\frac{2}{3}\] \[P(A/B')=\frac{P(A)(1-P(B))}{(1-P(B))}=\frac{\frac{1}{3}.\frac{5}{6}}{\frac{5}{6}}=\frac{1}{3}\] \[P(A/A\cup B)=\frac{P(A\cap (A\cup B))}{P(A\cup B)}\] \[=\frac{P(A)}{P(A\cup B)}\] \[\frac{\frac{1}{3}}{\frac{1}{3}+\frac{1}{6}-\frac{1}{18}}\] \[=\frac{6}{6+3-1}=\frac{3}{4}\] \[\therefore \] Option (3) is correct


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