Question
What is the average of the squares of the first 25 natural
numbers?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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