JEE Main & Advanced Mathematics Probability Question Bank Definition of probability

  • question_answer
    A man and a woman appear in an interview for two vacancies in the same post. The probability of man's selection is 1/4 and that of the woman's selection is 1/3. What is the probability that none of them will be selected [MNR 1988]

    A)                 \[\frac{1}{2}\]       

    B)                 \[\frac{1}{12}\]

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

    D)                 None of these

    Correct Answer: A

    Solution :

               Let \[{{E}_{1}}\] be the event that man will be selected and \[{{E}_{2}}\] the event that woman will be selected. Then            \[P({{E}_{1}})=\frac{1}{4}\] so \[P({{\bar{E}}_{1}})=1-\frac{1}{4}=\frac{3}{4}\] and \[P({{E}_{2}})=\frac{1}{3}\]            So \[P({{\bar{E}}_{2}})=\frac{2}{3}\]            Clearly \[{{E}_{1}}\] and \[{{E}_{2}}\] are independent events.                 So, \[P({{\bar{E}}_{1}}\cap {{\bar{E}}_{2}})=P({{\bar{E}}_{1}})\times P({{\bar{E}}_{2}})=\frac{3}{4}\times \frac{2}{3}=\frac{1}{2}\].


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