JCECE Engineering JCECE Engineering Solved Paper-2008

  • question_answer
    The records of a hospital show that \[10%\] of the cases of a certain disease are fatal. If \[6\] patients are suffering from the disease, then the probability that only three will die, is

    A) \[8748\times {{10}^{-5}}\]                           

    B) \[1458\times {{10}^{-5}}\]

    C) \[1458\times {{10}^{-6}}\]                           

    D) \[41\times {{10}^{-6}}\]

    Correct Answer: B

    Solution :

    The probability of suffering from a diseases is\[10%\]. \[ie,\]                    \[p=\frac{10}{100}=\frac{1}{10}\] and probability of not suffering from a diseases is                                \[q=1-\frac{1}{10}=\frac{9}{10}\] Total number of patients,\[n=6\] \[\therefore \]Required probability                 \[{{=}^{6}}{{C}_{3}}{{\left( \frac{1}{10} \right)}^{3}}{{\left( \frac{9}{10} \right)}^{3}}\]                 \[=\frac{6\cdot 5\cdot 4}{3\cdot 2\cdot 1}\times \frac{1}{1000}\times \frac{9\times 9\times 9}{1000}\]                 \[=\frac{20}{{{10}^{6}}}\times 729=\frac{2}{{{10}^{5}}}\times 729\]                 \[=1458\times {{10}^{-5}}\]


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