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    Question

    What is the average of the squares of the first 31 natural

    numbers?
    A 324 Correct Answer Incorrect Answer
    B 330 Correct Answer Incorrect Answer
    C 336 Correct Answer Incorrect Answer
    D 342 Correct Answer Incorrect Answer

    Solution

    Sum of squares of first 'n' natural numbers = n × (n + 1) × (2n + 1) ÷ 6
    So, average = n × (n + 1) × (2n + 1) ÷ 6n = (n + 1) × (2n + 1) ÷ 6
    = (31 + 1) × (2 × 31 + 1) ÷ 6
    = 32 × 63 ÷ 6

    = 336

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