Question

    Three numbers are in the ratio 1:2:2, and the sum of their

    squares is 225. What is the average of the two largest numbers?
    A 5 Correct Answer Incorrect Answer
    B 10 Correct Answer Incorrect Answer
    C 12 Correct Answer Incorrect Answer
    D 22 Correct Answer Incorrect Answer

    Solution

    ATQ;
    Let the numbers be x, 2x, and 2x.

    Then:

    x² + (2x)² + (2x)² = 225

    ⇒ x² + 4x² + 4x² = 225

    ⇒ 9x² = 225

    ⇒ x² = 25

    ⇒ x = 5

    So, the numbers are 5, 10, 10

    Required average = (10 + 10) ÷ 2 = 10

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