Question

    Out of 180 litres of paint mixture, the ratio of red to

    blue paint is 5:4. What quantity of red paint should be added to make the ratio 7:5?
    A 25 litres Correct Answer Incorrect Answer
    B 35 litres Correct Answer Incorrect Answer
    C 20 litres Correct Answer Incorrect Answer
    D 12 litres Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    ATQ,

    Red paint = (5/9) × 180 = 100 litres

    Blue paint = (4/9) × 180 = 80 litres

    Let red paint added = x litres

    Then, (100 + x) : 80 = 7 : 5

    So, 100 + x = (7/5) × 80 = 112

    x = 112 - 100 = 12 litres

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