1. Average of the first 5 natural numbers is?
a. 5
b. 4 c. 3 d. 2 The answer is (c) Sum of first 5 natural numbers= (1+2+3+4+5)= 15 Average of first 5 natural numbers= 15/5= 3

2. What is the average of all odd numbers upto 100?

Sum of all odd numbers till 100 is 2500(i.e. 50 numbers) Average= 2500/50=50

3. 36a + 36b = 576. What is the average of a & b?

36a + 36b = 576 36( a+b ) = 576 a+b = 576/36 = 16 Average of a & b = (sum of a & b )/ 2 = 16 / 2 = 8

4. The average of 11, 23 & x is 40. What is value of x ?

average of 11, 23 & x = 40 (11 + 23 + x) / 3 = 40 34 + x = 40 *3 x = 120 – 34 = 86

5. What is the average of first 10 multiples of 3?

average of first 10 multiples of 3=165/10 =16.5

6. What is the average of the following numbers?
42 34 56 58 60

average of numbers is 250/5 =50

7. If the average of 25 student’s age is 17. If we include the age of the teacher the average increase by 1. What is the age of the teacher?

a. 35 yr

b. 43 yr

c. 48 yr

d. 53 yr
The answer is (b)

Consider x= 25, y=17 yr z=18 yr
Age of the teacher= 18+25(18-17)= 43 yr

8. What is the average of the first 49 natural numbers?

a. 26

b. 25.5

c. 25

d. 24.5
e. None of above
The answer is (c)

average of natural number is n(n+1)/2*n = (n+1)/2
= (49+1)/2= 25