Dear Aspirants,
Welcome to Mentor for Bank Exams. Here I have collected the Important Problems
on averages for upcoming competitive Exams. Aspirants who are preparing for upcoming
for upcoming bank, insurance, ssc and railway exams 2019. Practice lot of
questions to become an expert in solving average problems and learn to use
shortcuts.
1. The average weight of a class comprising 25 students is 65 kg. The
average weight of 13 students is 70 kg. What is the approximate average weight
of the remaining students in the class?
a) 60 kg
b) 57 kg
c) 62 kg
d) 51 kg
e) 67 kg
Answer: A)
Total weight of 25 students = 25 X 65
= 1625 kg
Total weight of 13 students = 13 X 70
= 910 kg
Total weight of the remaining
students = 1625 - 910 = 715 kg
Average weight of the remaining
students = 715/12 = 59.58 kg ≈ 60 kg
2. There are 9 persons standing from left to right. The average age of 1st
five persons from left is 42 years, while the average age of first five persons
from right is 54 years. If the average age of all persons is 50 years, then
find the age of the middle person.
a) 32 years
b) 30 years
c) 36 years
d) 42 years
e) None of the above
Answer: B)
Total age of 1st five
persons from left = 42 × 5 = 210 years
Total age of 1st five
persons from right = 54 × 5 = 270 years
Total age of all persons = 50 × 9 =
450 years
The age of the middle person = 210 +
270 – 450 = 30 years
3. In an examination, a pupil’s average marks were 63 per paper. If he
had obtained 20 more marks for his Geography paper and 2 more marks for his
History paper, his average per paper would have been 65. How many papers were
there in the examination?
a) 8
b) 10
c) 11
d) 12
e) 14
Answer: C)
Let the numbers of papers be x.
Then, 63x + 20 + 2 = 65x (or)
2x = 22 (or)
x = 11.
4. The average marks obtained by 120 candidates in a 10th board
examinations 35. If the average marks of passed candidate is 39 and that of the
failed candidates is 15, what is the number of candidates who passed the board
examination?
a) 110
b) 115
c) 120
d) 100
e) 105
Answer: D)
Let No.of passed candidates are X
So, x*39 + (120 – x)15 = 120*35
=> x = 100
5. 3 years ago, the average of a family of 5 members was 17 years. A baby
having been born, the average age of the family is the same today. The present
age of the baby is:
a) 5 years
b) 2 years
c) 1 year
d) 4 years
e) None of these
Answer: B)
Total age of 5 members, 3 years ago =
(17 x 5) years = 85 years
Total age of 5 members now = (85 + 3
x 5) years = 100 years
Total age of 6 members now = (17 x 6)
years = 102 years
Age of the baby = (102 – 100) years =
2 years
6. There were 35 students in a hostel. If the number of students increase
by 7, the expenses of the mess increase by Rs 42 per day while the average
expenditure per head diminishes by Rs 1. Find the original expenditure of the
mess?
a) 450
b) 420
c) 430
d) 410
e) None of these
Answer: B)
Suppose the average expenditure was
Rs a.
Then total expenditure = 35a
When 7 more students join the mess,
total expenditure = 35a + 42
Now, the average expenditure=
(35a+42) / (35 + 7)
Now, we have (35a + 42)/ 42 =(a – 1)
or, 35a + 42 = 42a – 42
7a = 84
a = 12
7. The average height of 27 persons was recorded as 162 cm. height of
Shreyas was deleted from the observation, the average height reduced by 1 cm. What
was Shreyas’ height?
a) 184 cm.
b) 226 cm.
c) 179 cm
d) 186 cm.
e) None of these
Answer: D)
Height of Shreyas = 162 + 26 = 188 cm
8. The average of 5 numbers is 306.4. The average of the first two
numbers is 431 and the average of the last two numbers is 214.5.What is the
third number?
a) 108
b) 52
c) 321
d) Cannot be determined
e) None of these
Answer: E)
According to the question,
Sum of five numbers = 5 × 3.6.4 =
1532
∴ Third number
= 1532 – 2 × 431 - 2 × 214.5
= 1532 – 862 – 429 = 241
9. Kamlesh bought 65 books for Rs. 1,050 from one shop and 50 books for
Rs. 1,020 from another. What is the average price he paid per book?
a) Rs. 36.4
b) Rs. 18.20
c) Rs. 24
d) Rs. 18
e) None of these
Answer: D)
Required average
= (1050 + 1020)/(65 + 50)
= 2070/115 = Rs. 18
10. The sum of five numbers is 290.The average of the first two numbers
is 48.5 and the average of last two numbers is 53.5. What is the third number?
a) 72
b) 84
c) 96
d) 108
e) None of these
Answer: E)
Third number
= 290 – 2 × 48.5 – 2 × 53.5
= 290 – 97 – 107 = 86
