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The average of the squares of the first 45 natural numbers is
Question

The average of the squares of the first 45 natural numbers is

A.

698.67

B.

699.67

C.

697.67

D.

696.67

Correct option is C

Given:
to find the average of the squares of the first 45 natural numbers.
Formula Used:
Sum of squares=n(n+1)(2n+1)6\text{Sum of squares} = \frac{n(n+1)(2n+1)}{6}​​
Average=Sum of squares of first n natural numbersn\text{Average} = \frac{\text{Sum of squares of first } n \text{ natural numbers}}{n}​​
Solution:
sum of squares of the first 45 natural numbers:
=45(45+1)(2(45)+1)6 =45×46×916=31,395= \frac{45(45+1)(2(45)+1)}{6}\\ \ \\ = \frac{45 \times 46 \times 91}{6} = 31,395​​
Now,
Average=31,39545=697.67\text{Average} = \frac{31,395}{45} = 697.67​​
Thus, the average of the squares of the first 45 natural numbers is 697.67.

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