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

  • question_answer
    In a book of 500 pages, it is found that there are 250 typing errors. Assume that Poisson law holds for the number of errors per page. Then, the probability that a random sample of 2 pages will contain no error, is

    A)  \[{{e}^{-0.3}}\]

    B) \[{{e}^{-0.5}}\]

    C)  \[{{e}^{-1}}\]

    D) \[{{e}^{-2}}\]

    Correct Answer: C

    Solution :

    [c] Here number of erros per page \[=\frac{250}{500}=\frac{1}{2}\] And \[n=2\therefore \lambda =np=2\times \frac{1}{2}=1\] And probability of no error \[P(X=0)=\frac{{{e}^{-1}}\times {{(1)}^{0}}}{0!}={{e}^{-1}}\]


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