Question

    A bag contains 7 blue balls, 3 red balls, and the rest

    are black balls. The probability of drawing a black ball from the bag is 4/9. How many black balls are there in the bag?
    A 9 Correct Answer Incorrect Answer
    B 6 Correct Answer Incorrect Answer
    C 5 Correct Answer Incorrect Answer
    D 4 Correct Answer Incorrect Answer
    E 8 Correct Answer Incorrect Answer

    Solution

    Let the number of black balls be 'y'. ATQ, y ÷ (y + 7 + 3) = (4/9) Or, 9y = 4 X (y + 10) Or, 9y = 4y + 40 Or, 5y = 40 So, 'y' = 8

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