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    Question

    A bag contains 8 blue balls, 7 green balls and 5 yellow

    balls. Three balls are drawn at random. Find the probability that at least two balls are green.
    A (23/114) Correct Answer Incorrect Answer
    B (7/34) Correct Answer Incorrect Answer
    C (77/285) Correct Answer Incorrect Answer
    D (4/19) Correct Answer Incorrect Answer
    E (18/95) Correct Answer Incorrect Answer

    Solution

    Total balls = 8 + 7 + 5 = 20
    Required probability = (Two green and one other) + (Three green)

    = 3 ├Ч [(7/20) ├Ч (6/19) ├Ч (13/18)] + (7/20 ├Ч 6/19 ├Ч 5/18)
    = (1638/6840) + (210/6840)
    = (1848/6840) = (77/285)

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