### The average of the squares of first ten natural numbers is.

A. 35.5 B. 36 C. 37.5 D. 38.5 Answer: Option D

### Solution(By Apex Team)

As we know that average of square of “n” natural number is $\begin{array}{l}=\Large\frac{n(n+1)(2n+1)}{6n}\\ =\Large\frac{(n+1)(2n+1)}{6}\end{array}$ According to the question, Average of square of first ten natural number is $\begin{array}{l}=\Large\frac{(10+1)(20+1)}{6}\\ =\Large\frac{11\times21}{6}\\ =38.5\end{array}$

## Related Questions On Average

A. 20
B. 21
C. 28
D. 32

A. 18
B. 20
C. 24
D. 30

A. 10 years
B. 10.5 years
C. 11 years
D. 12 years

### If the arithmetic mean of 0, 5, 4, 3 is a, that of -1, 0, 1, 5, 4, 3 is b and that of 5, 4, 3 is c, then the relation between a, b, and c is.

A. a = b = c
B. a : b : c = 3 : 2 : 4
C. 4a = 5b = c
D. a + b + c = 12