UPSC NDA Math Model Paper 1

Concept:
Suppose there are 'n' observations {x1,x2,x3,...,xn}
Mean (x)=‌

(x1+x2+x3+...+xn)

n

=‌

n ∑ i=1 xi

n

Sum of the natural numbers =‌

n(n+1)

2

Calculation:
To find: Mean of first n natural numbers
As we know, Sum of first n natural numbers =‌

n(n+1)

2

Now, Mean =‌

‌ n(n+1) 2

n

=‌

(n+1)

2