Railways Sample Paper RRB (Assistant Loco Pilot & Technician) Sample Test Paper-4

  • question_answer
    Arun contains 9 blue, 7 white and 4 black balls. If 2 balls are drawn at random, then what is the probability that only one ball is white?

    A)  \[\frac{71}{190}\]             

    B)       \[\frac{121}{190}\]

    C)   \[\frac{91}{190}\]              

    D)       \[\frac{93}{190}\]

    Correct Answer: C

    Solution :

     Total possible outcomes      \[=20{{c}_{2}}\,=\frac{20\,\,\,\,\,19}{1\,\,\,\,\,\,\,2}=190\] Total favourable outcomes             \[={{7}_{C1}}\,\,\,\,{{13}_{C1}}\,\,=\,\,7\,\,\,13\,\,=91\] \[\therefore \] Required probability \[=\frac{91}{190}\]

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