Banking Sample Paper SBI Junior Associates (Main) Sample Paper Test-3

  • question_answer
    In a class there are 12 boys and 8 girls. Five students are selected at random. What is the probability that 4 boys and 1 girl are selected?

    A)  \[\frac{231}{646}\]               

    B)  \[\frac{274}{637}\]   

    C)       \[\frac{215}{615}\]   

    D)       \[\frac{240}{637}\]   

    E)       \[\frac{165}{646}\]

    Correct Answer: E

    Solution :

    Total number of students\[=12+8=20\] \[\therefore n(S){{=}^{2n}}{{C}_{5}}=\frac{20\times 19\times 18\times 17\times 16}{5\times 4\times 3\times 2\times 1}=15504\] \[n(E){{=}^{12}}{{C}_{4}}{{\times }^{8}}{{C}_{1}}\] \[=\frac{12\times 11\times 10\times 9}{1\times 2\times 3\times 4}\times 8=455\times 8=3960\] \[\therefore P(E)=\frac{n(E)}{n(S)}=\frac{3960}{15504}=\frac{165}{646}\]


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