The mean of the following data 12,22,32,42,........n2 is
The sum of the squares of the first n natural numbers is n(n+1)(2n+1)6. The mean is the sum divided by the number of terms. Therefore, the mean is
n(n+1)(2n+1)6n=(n+1)(2n+1)6
The sum of (n-1) terms of 1+(1+3)+(1+3+5)+.............is