RAJASTHAN ­ PET Rajasthan PET Solved Paper-2005

  • question_answer
    A pack of cards contains 4 aces, 4 kings, 4 queens and 4 jacks. Two cards are drawn at random from this pack without replacement. The probability that atleast one of them will be an aces, is

    A)  \[\frac{1}{5}\]

    B)  \[\frac{3}{16}\]

    C)  \[\frac{9}{20}\]

    D)  \[\frac{1}{9}\]

    Correct Answer: C

    Solution :

     Total cards in the pack =16 Number of ways of selecting two cards randomly\[{{=}^{16}}{{C}_{2}}\] \[\therefore \]Probability of getting atleast one ace \[=\frac{^{4}{{C}_{1}}{{\times }^{12}}{{C}_{1}}}{^{16}{{C}_{2}}}+\frac{^{4}{{C}_{2}}}{^{16}{{C}_{2}}}\] \[=\frac{4\times 12\times 2}{16\times 15}+\frac{4\times 3}{16\times 15}\] \[=\frac{96+12}{16\times 15}=\frac{108}{240}\] \[=\frac{9}{20}\]


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