Percentage Questions for CDS, CLAT and SSC Exams.
Percentage Quiz 7
Directions: Kindly study the following Questions carefully and choose the right answer:
1. 20 litres of a mixture contains 20% alcohol and the rest water. If 4 litres of water be mixed
in it, the percentage of alcohol in the new mixture will be
A. 33 % B. 16 % C. 25 % D. 12 %
2. The price of rice has increased by 60%. In order to restore the original price, the new price
must be reduced by
A. 33 % B. 37 % C. 40 % D. 45 %
3. The number that is to be added to 10% of 320 to have the sum as 30% of 230 is
A. 37 B. 32 C. 23 D. 73
4. Three sets of 40, 50 and 60 students appeared for an examination and the pass
percentage was 100, 90 and 80 respectively. The pass percentage of the whole set is
A. 88 % B. 84 % C. 88 % D. 84 %
5. In an examination A got 25% marks more than B, B got 10% less than C and C got 25%
more than D. If D got 320 marks out of 500, the marks obtained by A were
A. 405 B. 450 C. 360 D. 400
6. After the GST, market price of loose sugar decrease by 25% because of which Kavya now is
able to buy 1 kg more sugar for Rs. 30. Find the reduced rate of sugar per kilogram.
A. Rs. 17 B. Rs. 7 C. Rs. 10 D. Rs. 7
7. In an examination, 30% of the total students failed in Hindi, 45% failed in English and 20%
failed in both subjects. Find the percentage of those who passed in both subjects.
A. 35.7% B. 35% C. 40% D. 45%
8. Anish spends 25% of his salary on house rent, 5% on food, 15% on travel, 10% on clothes
and the remaining amount of Rs. 22500 is saved. What is Anish’s salary?
A. Rs. 40000 B. Rs.40500 C. Rs.45000 D. Rs. 50000
9. If each side of a cube is increased by 10% the volume of the cube will increase by
A. 30% B. 10% C. 33.1% D. 25%
10. If A’s salary is 25% more than that of B, then B’s salary is less than A’s by
A. 20% B. 40 % C. 45 % D. 33 %
Correct Answers:
1 2 3 4 5 6 7 8 9 10
B B A A B B D D C A
Explanations:
1.
20
Quantity of alcohol = × 20 = 4 litres
100
Quantity of water = 20 – 4 = 16 litres
Now, 4 litres of water be mixed in it, then new mixture = 20 + 4 = 24 litres
4 50 2
∴ Percentage of alcohol = × 100 = = 16 %
24 3 3
Hence, option (B) is correct.
2. We can find the reduction in price by applying the concept of constancy,
3
The increase in price = 60% =
5
3
∴ Increase in reduction =
5+3
3
=
8
3
Price reduction in % = × 100
8
75 1
= = 37 %
2 2
Hence, option (B) is correct.
3. Let the number be x.
According to the question,
10% of 320 + x = 30% of 230
10 30
⇒ × 320 + x = × 230
100 100
⇒ 32 + x = 69
⇒ x = 69 – 32 = 37
Hence, option (A) is correct..
4. There are three sets of 40, 50 and 60 students.
∴ Total students = 40 + 50 + 60 = 150
And, total passed students = 100% of 40 + 90% of 50 + 80% of 60 = 40 + 45 + 48 = 133
Now, required percentage
Total passed students 133 266 2
= × 100 = × 100 = = 88 %
Total students 150 3 3
Hence, option (A) is correct.
5. Method I :
Let D got 100 marks.
C got 25% marks more than D.
∴ Marks obtained by C = 125
B got 10% marks less than C.
90
∴ Marks obtained by B = 125 ×
100
A got 25% marks more than B.
90 125 1125
Marks obtained by A = 125 × × =
100 100 8
1125
Now, 100 : : : 320 : x
8
1125 × 320
⇒ x= = 450
8 × 100
____________________________________________
Method II :
Given that D's marks = 320
C got 25% marks more than D.
∴ Marks obtained by C = 320 + 25% of 320 = 320 + 80 = 400
B got 10% marks less than C.
∴ Marks obtained by B = 400 – 10% of 400 = 400 – 40 = 360
A got 25% marks more than B.
∴ Marks obtained by A = 360 + 25% of 360 = 360 + 90 = 450
Hence, option (B) is correct.
6. Approach I:
Note: We know that
Expenditure = Price × Consumption
Keeping the expenses constant between price and consumption if one goes up, the other goes down and vice-
versa.
Ex. If price goes up by 25% (1/4), then the consumption should go down by
1 1
= = 20% to keep the expenses same.
4+1 5
Here, reduction in price = 25% =
1 1
= = = 1 kg
4–1 3
∴ Increase in consumption will be
Which means kavya initially used to buy 3 kg sugar for 30/-
30
∴ Initial price of sugar = = 10/-
3
∴ Reduced price = (100 – 25)% of 10/-
= 75 × 10 = 7.5
1
or, Rs. 7
2
Approach II:
Let the actual price of sugar be Rs. x per kg.
∴ Reduced price of sugar
According to the question,
x 3x
= (100 – 25) × = Rs. per kg
100 4
30 30
– =1
3x x
4
40 30
or, – =1
x x
∴ x = Rs. 10 kg
3x
So, reduced rate of sugar per kg =
4
3 × 10 15 1
= = = Rs. 7
4 2 2
Hence, option B is correct.
7. Let the number of students be 100.
Number of students who failed in Hindi is 30%
∴ n(H) = 30
Number of students who failed in English is 45%
∴ n(E) = 45
Number of students who failed in both the subjects is 20%
n(H ∩ E) = 20
Applying the set theory rule,
n (H U E) = n(H) + n(E) – n(H ∩ E)
= 30 + 45 – 20 = 55
∴ Percentage of students who failed in Hindi or English or both the subjects = 55%
∴ Number of students who passed in both the subjects = 100 – 55 = 45%
Hence, option D is correct.
8. Remaining salary percent = [100 – (25 + 5 + 15 + 10)] = 100 – 55 = 45%
Let the total salary of Anish be x. Then,
According to the question,
45% of x = 22500
22500
⇒ x = × 100 = Rs. 50000
45
Hence, option D is correct.
9.
Volume of cube = (Edge)3 We can find the effective change by applying the net% effect.
xy
Net % effect = x + y + %
100
Here, x = y = 10%
10 × 10
= 10 + 10 + = 21%
100
Again, applying the net % effect formula Here, x = 21%, y = 10%
21 × 10
= 21 + 10 + = 31 + 2.1 = 33.1%
100
Hence, option C is correct.
10.
1
Given, A's salary is more than B's by 25% =
4
Applying the concept of constancy,
1 1
B's salary is less that A's = =
4+1 5
1
In percentage = × 100% = 20%
5
Hence, option A is correct.
