RAJASTHAN ­ PET Rajasthan PET Solved Paper-2012

  • question_answer
    A fair die is tossed eight times. The probability that a third six is observed on the eight throw is

    A)  \[\frac{^{7}{{C}_{2}}\times {{5}^{5}}}{{{6}^{7}}}\]

    B)  \[\frac{^{7}{{C}_{2}}\times {{5}^{5}}}{{{6}^{8}}}\]

    C)  \[\frac{^{7}{{C}_{2}}\times {{5}^{5}}}{{{6}^{6}}}\]

    D)  None of the above

    Correct Answer: B

    Solution :

    \[\therefore \]Required probability \[{{=}^{7}}{{C}_{2}}{{\left( \frac{1}{6} \right)}^{2}}{{\left( \frac{5}{6} \right)}^{5}}\times \frac{1}{6}\] \[=\frac{^{7}{{C}_{2}}\times {{5}^{5}}}{{{6}^{8}}}\]


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