Average - Aptitude Questions & Answers

Last Updated : 28 Mar, 2025

Average is a single number expressing a set of data. It is calculated by dividing the sum of the values in the set by their number, also called arithmetic mean. It is a very important concept for aptitude questions as it is used in almost every quantitative Concept like Profit & loss, Arithmetic progressions, mensuration, etc.

Prerequisites:

Aptitude Questions on Average

Following are some of the Average questions along with their solutions:

Question 1: The average monthly salary of A and B is Rs. 7000. The average monthly salary of B and C is Rs. 8500, and the average monthly salary of A and C is Rs. 9000. What is the monthly salary of A?

Solution:

Let A, B, and C represent their respective monthly salaries. Then, we have:
A + B = (7000 × 2) = 14000 .... (i)
B + C = (8500 × 2) = 17000 .... (ii)
A + C = (9000 × 2) = 18000 .... (iii)
Adding (i), (ii), and (iii), we get: 2(A + B + C) = 49000 or A + B + C = 24500 .... (iv)
Subtracting (ii) from (iv)
A + B + C = 24500 .... (iv) and B + C = 17000 .... (ii)
we get A = 7500.
A's monthly salary = Rs. 7500.

Question 2: The average age of a father, mother, and their daughter 4 years ago was 30 years, and that of the mother and daughter 6 years ago was 25 years. What is the present age of the father?

Solution:

Let the present ages of the father, mother, and daughter be F, M, and D, respectively.
The average age of the father, mother, and daughter 4 years ago was 30 years:
(F − 4) + (M − 4) + (D − 4)/3 = 30
Simplifying, we get:
F + M + D − 12 = 90 ⟹ F + M + D = 102 ... (i)
The average age of the mother and daughter 6 years ago was 25 years:
(M − 6) + (D − 6)/2 = 25
Simplifying, we get:
M + D − 12 = 50 ⟹ M + D = 62 ... (ii)
Now, we can substitute equation (ii) into equation (i):
F + (M + D) = 102 ⟹ F + 62 = 102
Solving for F:
F = 102 − 62 = 40
Thus, the present age of the father is 40 years.

Question 3: In the first 12 overs of a cricket match, the run rate was 5.5. What should be the run rate in the remaining 38 overs to reach the target of 300 runs?

Solution:

Calculate runs scored in the first 12 overs:
Runs scored = Run rate × Overs = 5.5 × 12 = 66 runs
Calculate runs still needed:
Runs needed = Target − Runs scored = 300 − 66 = 234 runs
Calculate the required run rate in the remaining 38 overs:
Required run rate = Runs needed/Remaining overs
= 234/38 ≈ 6.16
Since we need a whole number, we can round this up to 7 runs per over.
To reach the target of 300 runs, the required run rate in the remaining 38 overs is approximately 7 runs per over.

Question 4: A baker has sales of Rs. 7800, Rs. 8200, Rs. 7900, Rs. 8600, and Rs. 8100 for 5 consecutive months. How much sale must he have in the sixth month to achieve an average sale of Rs. 8000?

Solution:

Calculate the total sales needed for 6 months to achieve an average of Rs. 8000:
Total sales needed = Average sale × Number of months = 8000 × 6 = 48000.
Calculate the total sales for the first 5 months:
Total sale for 5 months = Rs. (7800 + 8200 + 7900 + 8600 + 8100) = Rs. 40600.
Required sale = Rs. (48000 - 40600)
= Rs. 7400.
The baker must have a sale of Rs. 7400 in the sixth month to achieve an average sale of Rs. 8000 over six months.

Question 5: A student's score was incorrectly recorded as 75 instead of 65. Because of this error, the class average increased by 0.4 marks. What is the total number of students in the class?

Solution:

Let n be the number of pupils in the class.
Let S be the original total marks of the class.
New total score:
S + (75 − 65) = S + 10
New average:
S + 10/n
Original average:
S/n
Equation based on the increase in average:
S + 10/n = S/n + 0.4
Multiply by n:
S + 10 = S + 0.4n
Simplify:
10 = 0.4n
Solve for n:
n = 10/0.4 = 25
Conclusion:
The total number of students in the class is 25.

Question 6: The average age of a basketball team of 12 players is 24 years. If the age of the coach is 5 years more than the average age of the team, and the average age of the remaining players is one year less than the average age of the whole team, what is the average age of the remaining players?

Solution:

Let the average age of the whole team be x.
Total age of the team = 11x
The total age of the captain and wicket keeper is:26 + 29 = 55
Total Age of Remaining Players =11x − 55
Average Age of Remaining Players = (11x − 55)/9
According to the problem, this average is one year less than the average age of the whole team:
(11x − 55)/9 = x − 1
11x − 9x = 55 − 9
2x = 46
x = 23
The average age of the team is 23 years.

Question 7: A grocery store purchases flour at Rs. 12, Rs. 15, and Rs. 18 per kilogram in three consecutive months. If the store spends Rs. 6000 each month, what is the average cost per kilogram of flour after the three months?

Solution:

Total quantity of flour consumed in 3 months:
Quantity = (6000/12 + 6000/15 + 6000/18)
Total Quantity = 500 + 400 + 333.33 ≈ 1233.33 kg
Total Amount = 6000 × 3 = 18000 Rs.
Average Cost = Total Quantity/Total Amount = 18000/1233.33 ≈ 14.59 Rs.
The average cost per kilogram of flour after the three months is approximately Rs. 14.59.

Question 8: If the average score of four groups of 30, 40, 35, and 50 students is 70, 75, 80, and 65 respectively, what is the overall average score of all the students combined?

Solution:

Required Average = (30 × 70) + (40 × 75) + (35 × 80) + (50 × 65)/30 + 40 + 35 + 50
Total Scores=2100 + 3000 + 2800 + 3250 = 11150
Total Students = 30 + 40 + 35 + 50 = 155
Overall Average = 11150/155 ≈ 71.94

Practice Questions on Average

The average salary of employees A and B is Rs. 6000, while the average salary of B and C is Rs. 7000, and the average salary of A and C is Rs. 8000. What is the monthly salary of B?
The average age of a mother, father, and their child 5 years ago was 35 years, and that of the father and child 7 years ago was 30 years. What is the present age of the mother?
In the first 10 overs of a cricket match, the run rate was 4.5. What should be the run rate in the remaining 40 overs to reach the target of 250 runs?
A shopkeeper has sales of Rs. 5000, Rs. 6000, Rs. 5500, Rs. 6200, and Rs. 5800 for 5 consecutive weeks. How much sale must he have in the sixth week to achieve an average sale of Rs. 6000?
A student's score was incorrectly recorded as 85 instead of 75. Because of this error, the class average increased by 0.5 marks. What is the total number of students in the class?
The average age of a football team of 15 players is 22 years. If the age of the coach is 3 years more than the average age of the team, what is the average age of the team including the coach?
A bakery purchases flour at Rs. 10, Rs. 13, and Rs. 15 per kilogram over three months. If the bakery spends Rs. 4000 each month, what is the average cost per kilogram of flour after the three months?
If the average score of three classes of 25, 30, and 35 students is 60, 70, and 80 respectively, what is the overall average score of all the students combined?

Answer Key

Salary of B: Rs. 5000
Present age of Mother: 46 years
Required run rate: 5.125 runs per over
Required sale for the sixth week: Rs. 7500
Total number of students: 20
Average age including coach: 22.19 years
Average cost per kg of flour: Rs. 12.31
Overall average score: 71.11

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