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JEE Main & Advanced Mathematics Probability Question Bank Self Evaluation Test - Probability-I

  • question_answer
    In four schools \[{{B}_{1}},{{B}_{2}},{{B}_{3}},{{B}_{4}}\] the percentage of girls students is 12, 20, 13, 17 respectively, From a school selected at random, one student is pick up at random and it is found that the student is girl, the probability that the school selected is  \[{{B}_{2,}}\]is

    A) \[\frac{6}{31}\]

    B) \[\frac{10}{31}\]

    C) \[\frac{13}{62}\]

    D) \[\frac{17}{62}\]

    Correct Answer: B

    Solution :

    [b] Total no. of students in four schools \[=12+20+13+17=62.\] Now, one students is selected at random. \[\therefore \] Total outcomes \[{{=}^{62}}{{C}_{1}}\] Now, no, of students in school \[{{B}_{2}}=20.\] No. of ways to select a student form \[{{B}_{2}}{{=}^{20}}{{C}_{1}}.\] \[\therefore \] Required probability \[=\frac{{{20}_{{{C}_{1}}}}}{{{62}_{{{C}_{1}}}}}=\frac{20}{62}=\frac{10}{31}\]


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