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Aptitude questions and answers on Average
1) What is the average of the first five multiples of 12?
- 36
- 38
- 40
- 42
The correct answer is A
Explanation -
Average = 12∗(1+2+3+4+5) ∗ 
= 12 ∗ 15∗ 
= 12 ∗ 3= 36
2) Average of five numbers is 20. If each number is multiplied by 2, what will be the new average?
- 30
- 40
- 50
- 60
The correct answer is B
Explanation -
The new average = Initial average ∗ 2
= 20 ∗ 2 = 40
3) If the average of three consecutive even numbers is 34, find the largest of these numbers.
- 30
- 32
- 34
- 36
The correct answer is D
Explanation -
Let the first number is X, then the next two even numbers would be X+2, X+4
As per question;
= 34
= 34
3X + 6 = 102
3X = 96
X = 32
Largest number would be = 32 + 4 = 36
4) 10 typists can type 600 pages in 8 hours.Find the average number of pages typed by each typist in an hour.
- 7 pages
- 7.5 pages
- 8 pages
- 8.5 pages
The correct answer is B
Explanation -
Total pages typed by 10 typists in 8 hours = 600
Pages typed by one typist in 8 hours = 
= 60 pages
Pages typed by one typist in one hour = 
= 7.5 pages
5) Average age of a group of 30 boys is 16 years. A boy of age 19 leaves the group and a new boy joins the group. If the new average age of the group is 15.8 years, find the age of the new boy.
- 12 years
- 13 years
- 14 years
- 15 years
The correct answer is B
Explanation -
Let the age of new boy = X years
Total age of 30 boys = 30*16 = 480 years
As per question, if we minus age of boy who leaves the group and then add the age of boy who joins the group the new average becomes = 15.8 years.
∴ 
= 15.8
480 - 19 + X = 474
X = 474 - 480 +19
X = - 6 +19
= 13 years
6) The average weight of 10 men is decreased by 2 kg when one of them whose weight is 60 kg is replaced by a new man. What is the weight of the new man?
- 35 kg
- 40 kg
- 45 kg
- 50 kg
The correct answer is B
Explanation -
The average decrease in weight per person = 2kg
There are 10 men so a total decrease in weight on replacing a man with a new man = 10 ∗ 2= 20 kg
Weight of the man who is replaced = 60 kg
∴The weight of the new man would be = Weight of man replaced - total decrease in weight of the group of 10 men.
= 60 - 20 = 40 kg
7) The average age of the committee of 10 members is 40 years. A member of age 52 retires and a new member of age 38 takes his place. What is the average age of the present committee?
- 38.6 years
- 33.5 years
- 35.5 years
- 37.5 years
The correct answer is A
Explanation -
Total age of the committee = 10 ∗ 40 = 400 years
Age of retired member = 52 years
Age of new member = 38 years
As per the question, we will minus 52 years and add 38 years in the total age then divide by 10 to find the new average age of the committee.
∴ 
= 
= 
= = 38.6 years
8) If the sum is 240 and the average is 40, find the number of quantities.
- 5
- 8
- 5
- 6
The correct answer is D
Explanation -
So, Number of Quantities =240/40
=6
9) Mohan gets a salary of Rs. 6435, Rs. 6927, Rs. 6855, Rs. 7230 and Rs. 6562 for 5 months. How much salary he must-have in the sixth month so that he gets an average of Rs. 6500?
- 4091
- 4991
- 3499
- 3344
The correct answer is B
Explanation -
Total salary for 5 months = Rs. (6435 + 6927 + 6855 + 7230 + 6562) = Rs. 34009.
Required salary = Rs. [ (6500 x 6) - 34009 ]
= Rs. (39000 - 34009)
= Rs. 4991
10) The average weight of 8 women increases by 2.5 kg when a new woman replaces one of them weighing 65 kg. Find the weight of the new woman.
- 20
- 85
- 67
- 80
The correct answer is B
Explanation -
Total weight increased = (8 x 2.5) kg = 20 kg.
So, weight of new woman = (65 + 20) kg = 85 kg.
11) The captain of a cricket team of 11 members is 26 years old, and the wicket-keeper is three years older than the captain. If the ages of captain and wicketkeeper are excluded, the average age of the remaining players of the team is one year less than the average age of the whole team. What is the average age of the team?
- 19
- 49
- 17
- 23
Answer: D
Explanation -
Let the average age of the whole team by x years.
11x - (26 + 29) = 9(x -1)
11x - 55 = 9x -9
11x - 9x = - 9 + 55
2x = 46
x = 23 Years.
12) Three years ago, the average age of Anita, Priya, and Varsha were 27 years. If five years ago, the average age of Priya and Varsha was 20 years, find the present age of Anita.
- 30
- 40
- 60
- 25
Answer: B
Explanation -
Sum of the present ages of Anita, Priya and Varsha = (27 x 3 + 3 x 3) years = 90 years.
Sum of the present ages of Priya and Varsha = (20 x 2 + 5 x 2) years = 50 years.
Anita`s present age = (90 - 50) years = 40 years.
13) In Varun`s opinion, his weight is greater than 65 kg but less than 72 kg. His father does not agree with Varun, and he thinks that Varun`s weight is greater than 60 kg but less than 70 kg. His sister`s view is that his weight cannot be greater than 68 kg. If all are correct in their estimation, what is the average of the different possible weights of Varun?
- 60
- 65
- 67
- 54
Answer: C
Explanation -
Let Arun`s weight by X kg.
According to Varun: 65 <<X < 72
According to Varun`s father: 60 < X < 70.
According to Varun`s sister: X <= 68
The different possible weights of Varun or the values that satisfy all the above conditions are 66, 67 and 68.
So, the Average of different possible weights of Varun = (66+67+68) / 3
= 201/3
= 67 k