New RBI Grade B 2025 Notification will come Soon! Enroll Here

    Question

    A bag contains 5 pink balls, 10 grey balls, and 3 brown

    balls. Two balls are drawn at random. Find the probability that the two balls are grey.
    A 11/51 Correct Answer Incorrect Answer
    B 5/17 Correct Answer Incorrect Answer
    C 20/153 Correct Answer Incorrect Answer
    D 5/51 Correct Answer Incorrect Answer
    E 10/51 Correct Answer Incorrect Answer

    Solution

    Number of ways of selecting two grey balls = 10 C₂
    Total number of balls = 5 + 10 + 3 = 18
    Number of ways of selecting two balls = 18C₂
    Probability = 10 C₂ ÷ 18 C₂ = (10 × 9) ÷ (18 × 17) = 90 ÷ 306 = 5/17

    Practice Next