VIT Engineering VIT Engineering Solved Paper-2007

  • question_answer
    If \[P(A)=\frac{1}{12},P(B)=\frac{5}{12}\] and \[P\left( \frac{B}{A} \right)=\frac{1}{15},\] then \[P(A\cup B)\]is equal to :

    A)  \[\frac{89}{180}\]

    B)  \[\frac{90}{180}\]

    C)  \[\frac{91}{180}\]

    D)  \[\frac{92}{180}\]

    Correct Answer: A

    Solution :

    \[\because \]\[P(A)=\frac{1}{12},P(B)=\frac{5}{12}\]and \[P\left( \frac{B}{A} \right)=\frac{1}{15}\] We know that \[P\left( \frac{B}{A} \right)=\frac{P(A\cap B)}{P(A)}\] \[\Rightarrow \] \[\frac{1}{15}=\frac{P(A\cap B)}{\frac{1}{12}}\] \[\Rightarrow \] \[P(A\cap B)=\frac{1}{180}\] Also, \[P(A\cup B)=P(A)+P(B)-P(A\cap B)\] \[=\frac{1}{12}+\frac{5}{12}-\frac{1}{180}\] \[=\frac{15+75-1}{180}=\frac{89}{180}\]


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