Question

What is the mean of the first ten natural numbers?

• A. 4.5
• B. 5.5
• C. 6.5
• D. 5

Answer 1

The correct option is B

5.5

The first 10 natural numbers are 1 to 10.

Sum of first n natural numbers = $\frac{n(n+1)}{2}$
here, n = 10
So, sum of first 10 natural numbers
= $\frac{10(10+1)}{2}$ = $\frac{10\times 11}{2}$ = $55$

Mean = $\frac{Sumoffirst10naturalnumbers}{n}$
Mean = $\frac{55}{10}$ = 5.5

Thus, 5.5 is the mean of the first ten natural numbers.