Aptitude Questions and Answers on Average with explanation

  
1. In the first 10 overs of a cricket game, the run rate was only 3.2. What should be the run rate in the remaining 40 overs to reach the target of 282 runs?
A. 6.25
B. 5.5
C. 7.4
D. 5

Answer : Option A

Explanation :
Runs scored in the first 10 overs = 10×3.2=32

Total runs = 282

remaining runs to be scored = 282 - 32 = 250

remaining overs = 40

Run rate needed = 25040=6.25


2. A grocer has a sale of Rs. 6435, Rs. 6927, Rs. 6855, Rs. 7230 and Rs. 6562 for 5 consecutive months. How much sale must he have in the sixth month so that he gets an average sale of Rs. 6500?

A. 4800
B. 4991
C. 5004
D. 5000

Answer : Option B

Explanation :
Let the sale in the sixth month = x
Then 6435+6927+6855+7230+6562+x6=6500

=> 6435 + 6927 + 6855+ 7230 + 6562 + x = 6 × 6500 = 39000

=> 34009 + x = 39000

=> x = 39000 - 34009 = 4991

3. The average of 20 numbers is zero. Of them, How many of them may be greater than zero , at the most?

A. 1
B. 20
C. 0
D. 19

Answer : Option D

Explanation :
Average of 20 numbers = 0
=>Sum of 20 numbers20=0

=> Sum of 20 numbers = 0

Hence at the most, there can be 19 positive numbers.

(Such that if the sum of these 19 positive numbers is x, 20th number will be -x)

4. The captain of a cricket team of 11 members is 26 years old and the wicket keeper is 3 years older. If the ages of these two are excluded, the average age of the remaining players is one year less than the average age of the whole team. Find out the average age of the team.
A. 23 years
B. 20 years
C. 24 years
D. 21 years

Answer : Option A

Explanation :
Number of members in the team = 11

Let the average age of of the team = x

=>Sum of the ages of all the 11 members of the team11=x

=> Sum of the ages of all the 11 members of the team = 11x


Age of the captain = 26

Age of the wicket keeper = 26 + 3 = 29

Sum of the ages of 9 members of the team excluding captain and wicket keeper

= 11x - 26 - 29 = 11x - 55

Average age of 9 members of the team excluding captain and wicket keeper

=11x559

Given that 11x559=(x1)

=> 11x - 55 = 9(x - 1)

=> 11x - 55 = 9x - 9

=> 2x = 46


=>x=462=23 years
5. The average monthly income of A and B is Rs. 5050. The average monthly income of B and C is Rs. 6250 and the average monthly income of A and C is Rs. 5200. What is the monthly income of A?
A. 2000
B. 3000
C. 4000
D. 5000

Answer : Option C

Explanation :
Let the monthly income of A = a

monthly income of B = b

monthly income of C = a
a+b=2×5050(Equation1)b+c=2×6250(Equation2)a+c=2×5200(Equation3)

(Equation 1) + (Equation 3) - (Equation 2)
=>a+b+a+c(b+c)=(2×5050)+(2×5200)(2×6250)

=> 2a = 2(5050 + 5200 - 6250)

=> a = 4000

=> Monthly income of A = 4000