Banking Quantitative Aptitude Sample Paper Quantitative Aptitude Sample Paper-27

  • question_answer
    A box contains 20 electric bulbs, out of which 4 are defective. Two bulbs are chosen at random from this box. The probability that atleast one of these is defective, is

    A) \[\frac{4}{19}\]                         

    B) \[\frac{7}{19}\]

    C) \[\frac{12}{19}\]                                   

    D) \[\frac{21}{95}\]

    Correct Answer: B

    Solution :

    P (None is defective) \[=\frac{{}^{16}{{C}_{2}}}{{}^{20}{{C}_{2}}}=\frac{12}{19}\]
    P (atleast one is defective) \[=\left( 1-\frac{12}{19} \right)=\frac{7}{19}\]


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