Aptitude test questions on average with answer and explanation.

1. Aptitude(Average)

2. Test number 1
1) What is the average of first five
multiples of 12?
1. 36
2. 38
3. 40
4. 42
The correct answer is 1
 Explanation:
Average = 12∗(1+2+3+4+5)
∗ 1/5
= 12 ∗ 15∗ 1/5
= 12 ∗ 3= 36

3. 2) Average of five numbers is 20.
If each number is multiplied by 2,
what will be the new average?
1. 30
2. 40
3. 50
4. 60
 The correct answer is 2
 Explanation:
The new average = Initial average
∗ 2
= 20 ∗ 2 = 40

4. 3) If the average of three consecutive
even numbers is 34, find the largest of
these numbers.
1. 30
2. 32
3. 34
4. 36
The correct answer is 4
 Explanation:
Let the first number is X, then the next
two even numbers would be X+2, X+4
As per question;
(X+X+2+X+4)/3 = 34
(3x+6)/3 = 34
3X + 6 = 102
3X = 96
X = 32
Largest number would be = 32 + 4 = 36

5. 4) 10 typists can type 600 pages
in 8 hours.Find the average
number of pages typed by each
typist in an hour.
1. 7 pages
2. 7.5 pages
3. 8 pages
4. 8.5 pages
 The correct answer is 2
 Explanation:
Total pages typed by 10 typists in
8 hours = 600
Pages typed by one typist in 8
hours = 600/10 = 60 pages
Pages typed by one typist in one
hour = 60/8 = 7.5 pages

6. Test no. 2
5) The average of Sohan's marks
in 6 subjects is 74. If his average
in five subjects excluding science
is 70, how many marks he
obtained in science?
1. 94
2. 92
3. 90
4. 88
 The correct answer is 1
 Explanation:
Total marks obtained in 6 subjects
= 6 ∗ 74 = 444
Total marks in 5 subjects
excluding science = 5 ∗ 70 = 350
Therefore, marks obtained in
science would be = 444 - 350 =
94

7. 6) 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.
1. 12 years
2. 13 years
3. 14 years
4. 15 years
 The correct answer is 2
 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

8. 7) 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?
1. 35 kg
2. 40 kg
3. 45 kg
4. 50 kg
 The correct answer is 2
 Explanation:
Average decrease in weight per
person = 2kg
There are 10 men so 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

9. 8) The average age of 30 boys in
a class is 15 years. If we include
the age of two teachers the
average age increases by 1. Find
the sum of ages of the two
teachers.
1. 55 years
2. 58 years
3. 62 years
4. 64 years
 The correct answer is 3
 Explanation:
Total age of 30 boys would be =
30∗15 = 450 years
Total age of 30 boys and 2
teachers would be = 32∗16= 512
years
∴ Sum of ages of two teachers
would be = 512 - 450 = 62 years

10. 9) 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?
1. 38.6 years
2. 33.5 years
3. 35.5 years
4. 37.5 years
 The correct answer is 1
 Explanation:
Total age of the committee = 10 ∗ 40 = 400
years
Age of retired member = 52 years
Age of new member = 38 years
As per 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.
∴
=(400-14)/10=386/10
=38.6 years

11. Test no. 3
10) Four years ago, the average
age of A and B was 20 years. If
today average age of A, B and C is
25 years, what will be age of C
after 7 years?
1. 32 years
2. 34 years
3. 36 years
4. 38 years
 The correct answer is 2
 Explanation:
Total age of A and B four years
ago = 20 ∗ 2 = 40 years
Present total age of A and B would
be = 40 + 4∗2 = 48 years
Present total age of A, B and C is
= 25 ∗ 3 = 75 years
∴ Present age of C would be = 75
- 48 = 27 years
Age of C after 7 years = 27 + 7 =
34 years

12. 11) What is the average of first
five natural numbers?
1. 5
2. 2
3. 3
4. 4
 Answer: 3
 Explanation: Average=
Sum of quantities/Number of
quantities
Sum of first five natural numbers
=1+2+3+4+5 = 15
Number of quantities = 5
On putting these values in
formula:
Average = 15/5
= 3

13. 12) If the sum is 240 and average
is 40, find the number of
quantities.
1. 5
2. 8
3. 5
4. 6
 Answer: 4
 Explanation:
So, Number of Quantities
=240/40
=6

14. 13) A group consists of two male,
two female and three children.
The average age of the male is 67
years, that of the female is 35
years, and that of the children is
six years. What is the average age
of the group?
1. 30.71
2. 31.71
3. 28.71
4. 35.45
 Answer: 2
 Explanation:
Average = (67*2+35*2+6*3)
/7
= (134+70+18) /7
= 222 /7
= 31.71

15. 14) 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?
1. 4091
2. 4991
3. 3499
4. 3344
 Answer: 2
 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

16. 15) If the average of 20 numbers
is zero, how many numbers may
be greater than zero?
1. 19
2. 49
3. 17
4. 33
 Answer: 1
 Explanation:
Average of 20 numbers = 0.
Sum of 20 numbers = (0 x 20)
= 0.
So, it is quite possible that 19
of these numbers may be
positive and if their sum is "X"
then 20th number will be (-X).

17. Test no. 4
16) 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.
1. 20
2. 85
3. 67
4. 80
 Answer: 2
 Explanation:
Total weight increased = (8 x
2.5) kg = 20 kg.
So, weight of new woman =
(65 + 20) kg = 85 kg.

18. 17) 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?
1. 19
2. 49
3. 17
4. 23
 Answer: 4
 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.

19. 18) The average monthly income of
Rakesh and Suresh is Rs. 5050. The
average monthly income of Suresh
and Ramesh is Rs. 6250 and the
average monthly income of Rakesh
and Ramesh is Rs. 5200. What is
the monthly income of Rakesh?
1. 3000
2. 6000
3. 4000
4. 2500
 Answer: 3
 Explanation:
Rakesh +Suresh (total income)
= 5050 x 2 = 10100.... (i)
Suresh +Ramesh (total income)
= 6250 x 2 = 12500.... (ii)
Rakesh+ Ramesh (total income)
= 5200 x 2 = 10400.... (iii)
Adding (i), (ii) and (iii), we get: 2(P
+ Q + R) = 33000 or P + Q + R =
16500.... (iv)
Subtracting (ii) from (iv), we get P
= 4000.
So, Rakesh's monthly income = Rs.
4000.

20. 19) Three years ago, the average
age of Anita, Priya, and Varsha
was 27 years. If five years ago,
the average age of Priya and
Varsha was 20 years, find the
present age of Anita.
1. 30
2. 40
3. 60
4. 25
 Answer: 2
 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.

21. 20) 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?
1. 60
2. 65
3. 67
4. 54
 Answer: 3
 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 kg.

22. Test no. 5
21) The average weight of P, Q
and R is 45 kg. If the average
weight of P and Q is 40 kg and
that of Q and R is 43 kg, what is
the weight of Q?
1. 32
2. 65
3. 67
4. 31
 Answer: 4
 Explanation:
Let P, Q, R represent their
respective weights. Then, we
have:
P + Q + R = (45 x 3) = 135....
(i)
P + Q = (40 x 2) = 80.... (ii)
Q + R = (43 x 2) = 86.... (iii)
Adding (ii) and (iii), we get: P
+ 2Q + R = 166.... (iv)
Subtracting (i) from (iv), we
get: Q = 31.

23. 22) The average weight of 16
students in a class is 50.25 kg,
and that of the remaining 8
students is 45.15 kg. Find the
average weight of all the students
in the class.
1. 34.56
2. 56.23
3. 48.55
4. 31.44
 Answer: 3
 Explanation:

= 1165.20/24
= 48.55

24. 23) A museum has an average of
510 visitors on Sunday and 240
on other days. Find the average
number of visitors per day in a
month of 30 days beginning with
a Sunday.
1. 285
2. 275
3. 237
4. 245
 Answer: 1
 Explanation:
Since, the month begins with a
Sunday, so there will be 5
Sundays and 25 other days in
this month.
So, the average no. of visitor
per day
= 285

25. 24) If the average marks of three
classes of 45, 60 and 55 students
are 60, 55, 50 respectively, find
the average marks of all the
students.
1. 52.85
2. 45.75
3. 64.68
4. 54.68
 Answer: 4
 Explanation:
= (2700+3300+2750/160)
= 8750/160
= 54.68

26. 25) In a class average age of 15
boys is 11. If 5 boys each of age 9
years are added, what would be
the new average?
1. 20 years
2. 10 years
3. 10.5 years
4. 23 years
 Answer: 3
 Explanation:
Sum of ages of 15 boys =
15*11=165
Sum of ages of 5 boys = 5*9
=45
Total age of 20 boys = 165+45
= 210
Average of ages of 20 boys =
210/20= 10.5 years

27. Test no. 6
26) If the number of quantities in
group A is 10 and in group B is 8,
and their individual average is 24
and 16 respectively, find the
combined average of the two
groups.
1. 20.44
2. 18.22
3. 16.22
4. 18.66
 Answer: 1
 Explanation:
The combined average of the
two groups is =
=(10*24+8*16)/(10+8)
= (240+128)/18
= 368/18
= 20.44

28. 27) The average of square of first
6 consecutive even numbers is:
1. 12.20
2. 60.66
3. 16.45
4. 178
 Answer: 2
 Explanation:
 Here, n=6
So, Average = 2 (6+1)
(2*6+1)/3
=2*7*13/3
= 182 /3
= 60.66

29. 28) Find the average of first 4
consecutive even numbers.
1. 2
2. 5
3. 1
4. 8
 Answer: 2
 Explanation:
Average of first n consecutive
even numbers is given by:
Average= n+1
Here, n=4
So, the average = 4+1=5

30. 29) Find the average of first 5
consecutive even numbers
starting from 2 to 10, where the
last even number is 10.
1. 1
2. 6
3. 2
4. 8
 Answer: 2
 Explanation:
The average of first n
consecutive even numbers
starting from 2 to X, where the
last even number is X, is given
by:
= (X+2)/2
Here, X=10
So, the required average =
(10+2)/2
= 12/2
=6

31. 30) Find the average of the
square of first 6 consecutive even
numbers starting from 2 to 12,
where the last even number is 12.
1. 12.20
2. 60.66
3. 16.45
4. 178
 Answer: 2
 Explanation:
=13*14/3
= 182/3
= 60.66

32. Test no. 7
31) Find the average of first 20
consecutive natural numbers.
1. 12.20
2. 10.78
3. 16.45
4. 10.5
 Answer: 4
 Explanation:
The average of first n
consecutive natural numbers is
given by;
=(n+1)/2
Here, n=20
So, average = (20+1)/2
=210/20
=21/2
=10.5

33. 32) Find the average of square of
first 5 consecutive natural
numbers.
1. 12
2. 10
3. 16
4. 11
 Answer: 4
 Explanation:
The average of square of first n
consecutive natural numbers is
given by;
= (n+1) (2n+1) / 6
Here, n=5
= (5+1) (2*5+1)/6
= 6*11/6
= 11

34. 33) Find the average of cubes of
first 7 consecutive natural
numbers.
1. 112
2. 110
3. 116
4. 113
 Answer: 1
 Explanation:
The average of cubes of first n
consecutive natural numbers is
given by;
= n (n+1)²/4
Here, n=7
= 7 (7+1)²/4
= 7*64/4
=448/4
= 112

35. 34) Find the average of first 8
consecutive odd numbers.
1. 11
2. 10
3. 8
4. 12
 Answer: 3
 Explanation:
The average of first n
consecutive odd numbers is
equal to n, so the average of
first 8 consecutive odd
numbers is 8.
You can check by solving it as
show below:
= (1+ 3+ 5+ 7+ 9+ 11+ 13+
15)/8
= 64/8 = 8

36. 35) Find the average of the
square of first 5 consecutive odd
numbers starting from 1 to 9,
where the last odd number is 9.
1. 22
2. 11
3. 16
4. 33
 Answer: 4
 Explanation:
The average of square of first n
consecutive odd numbers
starting from 1 to X, where the
last odd number is X, is given
by:
=X(X+2)/3
Here, X=9
So, average =9(9+2)/3
=9*11/3
=99/3
=33

37. Test no. 8
36) The average age of a group of
6 boys is 19. If the new average
age after a boy joins the group is
21.28, find the age of new boy.
1. Approx 23
2. Approx 32
3. Approx 35
4. Approx 45
 Answer: 3
 Explanation:
Use Formula:
Age of new body= New
average + Number of boys
initially * increase in average
= 21.28 + 6*2.28
=21.28 + 13.68
= 34.96

38. 37) The average weight of a
group of 5 boys is 26. If we
replace a boy of weight 25 in the
group with another boy so that
new average increases by 3, find
the weight of the new body.
1. 56
2. 34
3. 40
4. 33
 Answer: 3
 Explanation:
The weight of new person =
Weight of the removed person
+ No. of persons * Increase in
average.
= 25+5*3
=25+15
= 40

39. 38) Find the average of first 6
consecutive even numbers.
1. 6
2. 4
3. 0
4. 7
 Answer: 4
 Explanation:
The average of first n
consecutive even numbers is
given by:
= n+1
Here, n=6
= 6+1
= 7

40. 39) Find the average of first 9
consecutive odd numbers.
1. 9
2. 4
3. 0
4. 7
 Answer: 1
 Solution:
The average of first n
consecutive odd numbers is
equal to n.
Here, n=9
So, it is 9.

41. Reference
 https://www.javatpoint.com/aptitude/average

42. Thank you