JEE Main & Advanced Mathematics Probability Question Bank Binomial distribution

  • question_answer
    If X follows a binomial distribution with parameters \[n=6\]and \[p\]and \[4\,(P(X=4))=P(X=2),\] then \[p=\] [EAMCET 1994]

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

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

    C)                 \[\frac{1}{6}\]       

    D)                 \[\frac{1}{3}\]

    Correct Answer: D

    Solution :

               \[4P(X=4)=P(X=2)\Rightarrow 4.{}^{6}{{C}_{4}}{{p}^{4}}{{q}^{2}}={}^{6}{{C}_{2}}{{p}^{2}}{{q}^{4}}\]            \[\Rightarrow 4{{p}^{2}}={{q}^{2}}\Rightarrow 4{{p}^{2}}={{(1-p)}^{2}}\]                 \[\Rightarrow 3{{p}^{2}}+2p-1=0\Rightarrow p=\frac{1}{3}\].


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