Banking Sample Paper IBPS PO (Main) Sample Test Paper-1

  • question_answer
    Directions: Study the following information carefully and answer the questions that follow: A bag contains 2 red balls, 3 white balls and 5 pink balls.
    If three balls are chosen at random, what is the probability that at least one is red?

    A) \[\frac{7}{15}\]                         

    B) \[\frac{9}{22}\]             

    C) \[\frac{8}{23}\]             

    D)        \[\frac{8}{15}\]

    E)  None of these

    Correct Answer: D

    Solution :

    \[n(S){{=}^{10}}{{C}_{3}}\] \[n(E){{=}^{2}}{{C}_{1}}{{\times }^{8}}{{C}_{2}}{{+}^{2}}{{C}_{2}}{{\times }^{8}}{{C}_{1}}\] \[\therefore \]\[P(E)=\frac{^{2}{{C}_{1}}{{\times }^{8}}{{C}_{2}}{{+}^{2}}{{C}_{2}}{{\times }^{8}}{{C}_{1}}}{^{10}{{C}_{3}}}\] \[-\frac{(2\times 28)+(1\times 8)}{120}=\frac{64}{120}=\frac{8}{15}\]


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