Average Practice Questions

1) Question: The average weight of 25 students is 40 kg. If x new students join the class with an average weight of 52 kg, then the average weight of the class is increased by 2 kg. Find the value of x.
A.4
B.3
C.2
D.5 

Answer: D

Solution: 
According to the question,
25 * 40 + x * 52 = (25 + x) * (40 + 2)
1000 + 52x = (25 + x) * 42
52x – 42x = 1050 – 1000
10x = 50
x = 5 

2) Question: The average weight of 4 members group is 17 kg. If one new member is added to the group and then the average of the group is decreased by 3 kg, then find the weight of the new member.
A.1 kg
B.2 kg
C.3 kg
D.4 kg 

Answer: B

Solution: 
Total weight of group = 17 * 4 = 68 kg
Weight of new member = x
(x + 68)/5 = 14
x = 2 kg

3) Question: Average weight of 30 boys is 35 kg and the average weight of x girls is 40 kg. If the average weight of boys and girls together is 37 kg, then find the value of x?
A.50
B.25
C.20
D.45

Answer: C

Solution: 
30*35+x*40=37*(30+x)
1050+40x=1110+37x
3x=60
x=20

4) Question: Average weight of A, B, and C is 44 kg. If the average weight of A, B, and C is 10% more than the average weight of A, B, C, D, and E, then find the weight of D and E together.
A.68 kg
B.48 kg
C.56 kg
D.72 kg

Answer: A

Solution: 
The average weight of A, B, and C=44 kg
The average weight of A, B, C, D and
E=44*100/110=40 kg
The weight of D and E=40*5-44*3=68 kg

5) Question: Average salary of Venkat and Naveen is Rs.4000. If the salary of Venkat and Naveen is increased by 20% and 40% respectively then their total salary becomes Rs.10200. Find the difference between the increment amount of Naveen and the increment amount of Venkat.
A.Rs.500
B.Rs.1000
C.Rs.200
D.Rs.1500 

Answer: C
Solution:

Let the salary of Venkat = x
Total salary of Venkat and Naveen = 4000* 2=
8000
Let salary of Naveen = 8000 – x
[x*(120/100)] + [(8000 –x) * (140/100)] =
Rs.10200
12x/10 + 11200 – 14x/10= 10200
-2x/10 = -1000
x= 5000
Salary of venkat = Rs.5000
Salary of Naveen = 8000 – 5000 = Rs.3000
After the increment salary of Venkat = 5000*(120/100) = Rs.6000
Venkat’s Salary increment amount = 6000-5000 = Rs.1000
After the increment Naveen salary = 3000*(140/100) = Rs.4200
Naveen’s salary increment amount = Rs.4200 – 3000 = Rs.1200
Required difference = Rs.1200 – Rs.1000 = Rs.200

6) Question: 4 years ago, the average age of 6 persons in a family is x years. If a 2 year old baby is included in the family, then the average age of the family is x years. Find the value of x?
A.22
B.24
C.26
D.30

Answer: C

Solution:
(x + 4) *6 + 2 = 7x
6x + 24 + 2 = 7x
x = 26 

7) Question: The average of the three numbers is 10 and the ratio of the smallest 2 numbers is 4: 5. Find the difference between the highest and the second highest number, if the highest number is 4 more than the smallest number.
A.0
B.1
C.2
D.3

Answer:  C
Solution:

Let a < b < c
a = 4k, b = 5k and c = 4k + 4
(a + b+ c)/3 = 10
=> a + b + c = 30
=> 4k + 5k + 4 + 4k = 30
=> k = 2
c – b = (4 + 4k) – 5k
= 2 

8) Question: The average salary of all the employees in the company is Rs.6000. If the average salary of 60 employees in the same company is Rs.5400 and the average salary of the remaining employees in the company is Rs.7200. Find the total number of employees in the company?
A.100
B.120
C.110
D.90

Answer: D

Solution:
Total number of employees = x
The total salary of all the employees together =
6000 * x
Total salary of 60 employees = 60 * 5400 = 324000
Total salary of remaining employees = (x – 60) * 7200 = 7200x – 432000
6000x = 324000 + 7200x – 432000
x = 90

9) Question: Average age of five persons is 65 kg. If the average weight of the first two persons is 60 kg and the average weight of the last two persons is 75 kg, then find the average weight of the third person.
A.68 kg
B.72 kg
C.42 kg
D.55 kg

Answer: D

Solution: 
Weight of third person = x
65*5=2*60+75*2+x
325=120+150+x
x=55 kg

10) Question: In a dairy, there are 36 cows and the average weight of cows is 20 kg. If the average weight of 12 cows in the dairy is 24 kg while the average weight of 16 other cows in the dairy is 16 kg, then find the average weight of the remaining 8 cows in the dairy.
A.22 kg
B.15 kg
C.12 kg
D.24 kg

Answer: A

Solution: 
Total weight of dairy=36*20=720
Let the average weight of 8 cows=x
12*24+16*16+8*x=720
8*x=720-544
x=22 kg 

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