Question 63

The average of the square of first seven natural number is:

Solution

First seven natural numbers are : 1, 2, 3, 4, 5, 6, 7

As we know,

$$average\ =\ \frac{Sum\ of\ observations}{number\ of\ observations}$$

$$\ =\ \frac{1^2+2^2+3^2+4^2+5^2+6^2+7^2}{7}$$

$$\ =\ \frac{1+4+9+16+25+36+49}{7}$$

$$\ =\ \frac{140}{7}=20$$

Hence, Option D is correct.

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