Question

Find the arithmetic mean of first $10$ natural numbers.

• A. $55$
• B. $550$
• C. $5.5$
• D. None of the above

Answer 1

The correct option is C $5.5$

Arithmetic mean of first 10 natural numbers is:

$=\frac{1+2+3+4+5+6+7+8+9+10}{10}$

$=\frac{\left(\frac{n.(n+1)}{2}\right)}{10}$, where $n=10$.

$=\frac{\left(\frac{10.11}{2}\right)}{10}$

$=5.5$