JEE Main & Advanced AIEEE Solved Paper-2011

  • question_answer
    Consider 5 independent Bernoulli?s trials each with probability of success \[\rho \]. If the probability of at least one failure is greater than or equal to \[\frac{31}{32}\], then \[\rho \] lies in the interval.   AIEEE  Solved  Paper-2011

    A) \[\left( \frac{11}{12},1 \right]\]                    

    B) \[\left( \frac{1}{2},\frac{3}{4} \right]\]

    C) \[\left( \frac{3}{4},\frac{11}{12} \right]\]                 

    D) \[\left[ 0,\frac{1}{2} \right]\]

    Correct Answer: D

    Solution :

                 Probability of atleast one failure \[=1-\] no failure \[\ge \frac{31}{32}\] \[\Rightarrow 1-{{p}^{5}}\ge \frac{31}{32}\] \[\Rightarrow {{p}^{5}}\ge \frac{1}{32}\] \[\Rightarrow p\ge \frac{1}{2}\] Also \[p\ge 0\] Hence \[p\in \left[ 0,\frac{1}{2} \right]\] 


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