Question

    What is the average of the squares of the first 25 natural

    numbers?
    A 221 Correct Answer Incorrect Answer
    B 225 Correct Answer Incorrect Answer
    C 220 Correct Answer Incorrect Answer
    D 226 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
    = (25 + 1) × (2 × 25 + 1) ÷ 6
    = 26 × 51 ÷ 6
    = 221

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