If the arithmetic mean of the first natural numbers is 191,then the sum of the digits in n is

Arithmetic Mean = Sum of observations / Number of observations
Given,
Arithmetic mean of first n natural numbers = 191
Sum of first n natural numbers = n(n+1)/2
Arithmetic Mean = ( n(n+1)/2)/n
191 = (n(n+1)/2)/n
191n = n(n+1)/2
191n = (n^2+n)/2
382n = n^2+n
381n = n^2
n = 381( Number of Observations)
Sum of the first n natural numbers = n(n+1)/2
= 381(381+1)/2
=72,771
Sum of the digits in n = 72,771

answer = 12