JEE Main & Advanced Mathematics Probability Question Bank Binomial distribution

  • question_answer
    The probability that a man can hit  a target is \[\frac{3}{4}\]. He tries 5 times. The probability that he will hit the target at least three times is                                                [MNR 1994]

    A)                 \[\frac{291}{364}\]             

    B)                 \[\frac{371}{464}\]

    C)                 \[\frac{471}{502}\]             

    D)                 \[\frac{459}{512}\]

    Correct Answer: D

    Solution :

               We have \[p=\frac{3}{4}\Rightarrow q=\frac{1}{4}\] and \[n=5\]            Therefore required probability            \[={}^{5}{{C}_{3}}{{\left( \frac{3}{4} \right)}^{3}}{{\left( \frac{1}{4} \right)}^{2}}+{}^{5}{{C}_{4}}{{\left( \frac{3}{4} \right)}^{4}}\left( \frac{1}{4} \right)+{}^{5}{{C}_{5}}{{\left( \frac{3}{4} \right)}^{5}}\] \[=\frac{10\,.\,27}{{{4}^{5}}}+\frac{5\,.\,81}{{{4}^{5}}}+\frac{243}{{{4}^{5}}}=\frac{270+405+243}{1024}=\frac{459}{512}.\]


You need to login to perform this action.
You will be redirected in 3 sec spinner