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    Question

    An alloy contains 50% iron, 30% zinc, and 20% aluminum. How

    much iron should be added to 30 kg of the alloy so that the new alloy contains 60% iron?
    A 4 Correct Answer Incorrect Answer
    B 10 Correct Answer Incorrect Answer
    C 12 Correct Answer Incorrect Answer
    D Can’t be determined Correct Answer Incorrect Answer

    Solution

    ATQ,

    Quantity of the alloy = 30 kg

    Quantity of iron in 30 kg alloy = (0.50 × 30) = 15 kg

    Quantity of zinc in 30 kg alloy = (0.30 × 30) = 9 kg

    Quantity of aluminum in 30 kg alloy = (0.20 × 30) = 6 kg

    Let the quantity of iron to be added be x kg.

    According to the question,

    Quantity of iron in the new alloy = (Quantity of zinc + Quantity of aluminum)

    (15 + x) = (9 + 6)

    Or, x = 15 - 15 = 0

    No iron needs to be added as it already satisfies the condition.

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