JEE Main & Advanced Mathematics Question Bank Critical Thinking

  • question_answer
    The chance of an event happening is the square of the chance of a second event but the odds against the first are the cube of the odds against the second. The chances of the events are

    A)                 \[\frac{1}{9},\,\frac{1}{3}\]

    B)                 \[\frac{1}{16},\,\frac{1}{4}\]

    C)                 \[\frac{1}{4},\,\frac{1}{2}\]

    D)                 None of these

    Correct Answer: A

    Solution :

               Let \[{{p}_{1}},\,\,{{p}_{2}}\] be the chances of happenig of the first and second event respectively, then according to the given conditions, we have            \[{{p}_{1}}=p_{2}^{2}\] and \[\frac{1-{{p}_{1}}}{{{p}_{1}}}={{\left( \frac{1-{{p}_{2}}}{{{p}_{2}}} \right)}^{3}}\]                 \[\Rightarrow {{p}_{2}}=\frac{1}{3}\] and so \[{{p}_{1}}=\frac{1}{9}.\]


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