Question

show that the mean n first natural number is 1/2(n+1)

Answer 1

$\frac{1 + 2 + 3 + .....n}{n} \\ = \frac{n(n + 1)}{2n} \\ = \frac{1}{2} (n + 1)$
use sum of first n natural number = n(n+1)/2

Answer 2

see the attachment.........