Q. What will be the average of first 50 natural numbers?
Answer:
25.5
Notes: Because we know that the sum of first $n$ natural numbers is $(1+2+3+\ldots . .+ n )=n \frac{(n+1)}{2}$
so we can say that $(1+2+3+\ldots . .+50)=50 \frac{(50+1)}{2}=50 \times \frac{51}{2}=1275$
and the average of first 50 natural numbers $=\frac{1275}{50}=25.5$
Option [c] is the right answer.