What is the difference between the average of first 148 even positive numbers and the average of first 129 odd positive numbers?

A. 20

B. 23

C. 21

D. 19

Answer: Option A

Solution(By Examveda Team)

Average of first 148 positive number
$$\eqalign{ & = \frac{{N\left( {N + 1} \right)}}{N} \cr & = N + 1 \cr & = 148 + 1 \cr & = 149 \cr} $$
Average of first 129 odd number $$ = \frac{{{N^2}}}{N} = N = 129$$
Difference = 149 - 129 = 20