Failed to connect to MySQL: Access denied for user 'examnext_online'@'localhost' (using password: YES) The standard deviation of the set of first n natural numbers is - - Sarthaks eConnect

The standard deviation of the set of first n natural numbers is -

`sqrt(n^2-1)/(4n)`

`sqrt(n^2-1)/12`

`sqrt(n^2-1)/2`

`sqrt(n^2+1)/(2n)`