Question

    A bag contains 7 white balls, 5 black balls, and 4

    orange balls. Two balls are drawn at random. Find the probability that the two balls are white.
    A 7/17 Correct Answer Incorrect Answer
    B 1/4 Correct Answer Incorrect Answer
    C 7/20 Correct Answer Incorrect Answer
    D 3/8 Correct Answer Incorrect Answer

    Solution

    Number of ways of selecting two white balls = 7 C₂
    Total number of balls = 7 + 5 + 4 = 16
    Number of ways of selecting two balls = 16 C₂
    Probability = 7 C₂ ÷ 16 C₂ = (7 × 6) ÷ (16 × 15) = 42 ÷ 240 = 7/20

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