Percentage
Class 8th Mathematics RS Aggarwal Solution
- Express each of the following as a fraction: (i) 48% (ii) 220% (iii) 2.5%…
- Express each of the following as a decimal: (i) 6% (ii) 72% (iii) 125%…
- Express each of the following as a percentage: (i) 9/25 (ii) 3/125 (iii) 12/5…
- Convert the ratio 4 : 5 to percentage.
- Express 125% as a ratio.
- Which is largest in 6 2/3 % , 3/20 and 0.14?
- What per cent of 150 is 96?
- What per cent of 5 kg is 200 g?
- What per cent of 2 litres is 250 mL?
- Find 4 1/2 % of 3600.
- If 16% of number is 72, find the number.
- A man saves 18% of his monthly income. If he saves Rs. 3780 per month, what is…
- A football team wins 7 games, which is 35% of total games played. How many…
- Amit was given an increment of 20% on his salary. If his new salary is Rs.…
- Sonal attended her school on 204 days in a full year. If her attendance is 85%,…
- As income is 20% less than that of B. By what per cent is Bs income more than…
- The price of petrol goes up by 10%. By how much per cent must a motorist reduce…
- The population of a town increases by 8% annually. If the present population is…
- The value of a machine depreciates every year by 20%. If the present value of…
- An alloy contains 40% copper, 32% nickel and rest zinc. Find the mass of zinc…
- Balanced diet should contain 12% of proteins, 25% of fats and 63% of…
- Gunpowder contains 75% nitre and 10% sulphur. Find the amount of gunpowder…
- Divide Rs. 7000 among A, B and C such that A gets 50% of what B gets and B gets…
- Find the percentage of pure gold in 22-carat gold, if 24-carat gold is 100%…
- The salary of an officer is increased by 25%. By what per cent should the new…
- Choose the correct answer: 3/5 = ? A. 30 % B. 40 % C. 45 % D. 60 %…
- 0.8 % when expressed as a percentage, isA. 0.08 B. 0.008 C. 8 D. 0.8…
- 6:5 when expressed as a percentage, isA. 83 1/3 % B. 90 % C. 120 % D. 6.5 %…
- 5 % of a number is 9. The number isA. 45 B. 90 C. 135 D. 180
- What per cent of 90 is 120?A. 75 % B. 33 1/3 % C. 133 1/3 % D. none of these…
- What per cent of 10 kg 250 g?A. 25 % B. 5 % C. 10 % D. 2.5 %
- 40 % of ? = 240 A. 60 B. 600 C. 6000 D. 960
- ?% of 400 = 60A. 6 B. 12 C. 15 D. 20
- (180% of ?) / 2 = 504 A. 400 B. 480 C. 600 D. 560
- 20% or Rs. 800 = ?A. rs.160 B. rs.16 C. rs.1600 D. none of these
- In an examination, Nitin gets 98 marks. This amounts to 56% of the maximum…
- A number is first increased by 10% and then reduced by 10%. The numberA. does…
- A period of 4 hours 30 min is what per cent of a day?A. 18 3/4 % B. 20 % C. 16…
- In an examination, 65% of the total examines passed. If the number of failures…
- A number exceeds 20% of itself by 40. The number isA. 50B. 60C. 80D. 320…
- A number decreased by 27 1/2 % of itself by 87. The number isA. 58 B. 110 C.…
- 0.05 is what per cent of 20? A. 25 % B. 2.5 % C. 0.25 % D. 0.025 %…
- One-third of 1206 is what per cent of 134? A. 3 % B. 30 % C. 20 % D. 300 %…
- x% of y is y% of ? A. x B. 100x C. x/100 D. y/100
- What per cent of 2/7 is 1/35 ? A. 2.5 % B. 10 % C. 20 % D. 25 %
- 24% as a fraction; Express:
- 105% as a decimal; Express:
- 4 : 5 as a percentage; Express:
- 56% as a ratio. Express:
- If 34% of a number is 85, find the number.
- The value of a machine depreciates every year by 10%. If the present value of the…
- An alloy contains 30% copper, 42% nickel and rest zinc. Find the mass of zinc in 1 kg…
- In a class, 60% of the total number of students are boys and there are 14 girls. How…
- Which is largest in 8 1/3 % , 4/25 and 0.15?
- What per cent of 2/9 is 1/45 ? A. 2.5% B. 5% C. 7.5% D. 10%
- A number decreased by 30% gives 84. The number isA. 90 B. 110 C. 120 D. 135…
- (?)% of 320 is 48?A. 25% B. 15% C. 14% D. 9%
- What per cent of 45 is 54?A. 83 1/3 % B. 104% C. 108% D. 120%
- A number exceeds 25% of itself by 60. The number isA. 75 B. 45 C. 80 D. 65…
- 5% of which number is 12?A. 120 B. 180 C. 240 D. 320
- Fill in the blanks. (i) 7 1/2 % of Rs.1200 = .. (ii) 240 mL is% of 3 L. (iii) If x %…
- Write T for true and F for false for each of the following: (i) 6% of 8 is 48. (ii) 6…
Exercise 9a
Question 1.Express each of the following as a fraction:
(i) 48% (ii) 220% (iii) 2.5%
Answer:
(i) 48% means, 48 divided by 100.
So, 48% = 48 /100
= 12 /25
(ii) 220% means, 220 divided by 100.
So, 220% = 220 /100
= 11 /5
(ii) 2.5% means, 2.5 divided by 100.
So, 2.5% = 2.5 /100
= 1 /40
Question 2.
Express each of the following as a decimal:
(i) 6% (ii) 72% (iii) 125%
Answer:
(i) 6% means, 6 divided by 100.
So, 6% = 6 /100
= 3 /50 = 0.06
(ii) 72% means, 72 divided by 100.
So, 72% = 72 /100
= 18 /25 = 0.72
(iii) 125% means, 125 divided by 100.
So, 125% = 125 /100
= 5 /4 = 1.25
Question 3.
Express each of the following as a percentage:
(i) 
(ii) 
(iii) 
Answer:
(i) 
= ( x 100) %
= (9 x 4) %
= 36%
(ii) 
= ( x 100) %
= 2.4%
(iii) 
= ( x 100) %
= (12 x 20) %
= 240%
Question 4.
Convert the ratio 4 : 5 to percentage.
Answer:
4 : 5 = 
= (
x 100) % [Because 100% = 1]
= 80%
Question 5.
Express 125% as a ratio.
Answer:
125% = 125/100
= 5 /4 [Divided by 25]
= 5 : 4
Question 6.
Which is largest in
and
Answer:
= (20 /3) %
= (20 /3 x 1 /100)
= 1 /15
= 0.06 ____ (i)
= 0.15 ____ (ii)
0.14 ____ (iii)
From equation (i), (ii) and (iii),
0.15 > 0.14 > 0.06
Question 7.
What per cent of 150 is 96?
Answer:
Percentage = (96 /150 x 100) %
= (96 /3 x 2) % [Divided by 50]
= (32 x 2) %
= 64%
Question 8.
What per cent of 5 kg is 200 g?
Answer:
5 kg = 5 x 1000
= 5000 g
Now,
Percentage = (200 /5000 x 100) %
= (200 /50) % [Divided by 100]
= 4 %
Question 9.
What per cent of 2 litres is 250 mL?
Answer:
2 liters = 2 x 1000
= 2000 mL
Now,
Percentage = (250 /2000 x 100) %
= (250 /20) % [Divided by 100]
= 12.5 %
Question 10.
Find
of 3600.
Answer:
= (9 /2) x 100
= 9 /200
Now,
9 /200 of 3600 = 9 /200 x 3600
= 9 x 18 [Divided by 200]
= 162
Question 11.
If 16% of number is 72, find the number.
Answer:
Let the number = Z
∴ 16% of Z is 72.
⇒ 16 /100 × Z = 72
⇒ 16 Z = 7200
⇒ Z = 7200 /16
⇒ Z = 450
Question 12.
A man saves 18% of his monthly income. If he saves Rs. 3780 per month, what is his monthly income?
Answer:
Let Rs. Z his monthly income.
∴ Saving = 18% of Rs. Z
⇒ 3780 = 18 /100 × Z
⇒ 3780 = 9 /50 × Z
⇒ Z = 3780 × 50/9
⇒ Z = 420 × 50
[Because 420 × 9 = 3780]
⇒ Z = 21000
Therefore, his monthly income is Rs 21000/-
Question 13.
A football team wins 7 games, which is 35% of total games played. How many games were played in all?
Answer:
Let, total games played = Z
∴ percentage of games won = 35% of Z
⇒ 7 = 35/100 × Z
⇒ 7 = 7/20 × Z [Divided by 5]
⇒ Z = 7 × 20/7
⇒ Z = 20
Question 14.
Amit was given an increment of 20% on his salary. If his new salary is Rs. 30600, what was his salary before the increment?
Answer:
Let Amit’s old salary = Z
∴ Salary after increment = (Z + 20Z/100)
Now,
⇒ (Z + 20 Z/100) = 30600
⇒ (100 Z + 20 Z)/100 = 30600
⇒ 120 Z = 30600 × 100
⇒ Z = 25500
Question 15.
Sonal attended her school on 204 days in a full year. If her attendance is 85%, find the number of days on which the school was opened.
Answer:
Let the number of days the school was opened = Z
∴ Percentage of attendance = 85% of Z
Now,
85% of Z = 204
⇒ 85/100 × Z = 204
⇒ Z = 204 × 100/85
⇒ Z = 204 × 20/17 [Divided by 5]
⇒ Z = 12 × 20
⇒ Z = 240
Question 16.
A’s income is 20% less than that of B. By what per cent is B’s income more than A’s?
Answer:
Let B’s income = 100
Then, A’s income = (100 – 20) = 80
∴ B’s income more than A’s income = (100 – 80)/80 × 100
= 20/80 × 100
= 1/4 × 100
= 25
Question 17.
The price of petrol goes up by 10%. By how much per cent must a motorist reduce the consumption of petrol so that the expenditure on it remains unchanged?
Answer:
Let the consumption of petrol = 1 unit and its cost = Rs.100
∴ New cost of 1 unit of petrol = Rs.110
Now,
Rs.110 will yield 1 unit of petrol.
∴Rs.100 will yield (1/110 × 100)
= 10/11 unit of petrol
Now,
Reduction of consumption = 1 – (10/11)
= 1/11
Percentage of reduction = (1/11 × 100) %
= 
Question 18.
The population of a town increases by 8% annually. If the present population is 54000, what was it a year ago?
Answer:
Let population of the town a year ago = Z
∴ Present population = 108% of Z
⇒ 54000 = Z × 108/100
⇒ 54000 = Z × 27/25
⇒ Z = 54000 × 25/27
⇒ Z = 2000 × 25
⇒ Z = 50000
Question 19.
The value of a machine depreciates every year by 20%. If the present value of the machine be Rs. 160000, what was its value last year?
Answer:
Let the value of machine last year = Z
∴ Present value = (100 – 20) % of Z
⇒ 160000 = 80% of Z
⇒ 160000 = Z × 80/100
⇒ Z = 160000 × 100/80
⇒ Z = 2000 × 100
⇒ Z = 200000
Question 20.
An alloy contains 40% copper, 32% nickel and rest zinc. Find the mass of zinc in one kg of the alloy.
Answer:
Given,
Percentage of copper = 40%
Percentage of nickel = 32%
∴ Percentage of zinc = {100 – (40 + 32)} %
= 28 %
Now,
Mass of zinc in 1 kg of the alloy = (28 × 1/100) kg
= 0.28 kg
= 0.28 × 1000 g
= 280 g
Question 21.
Balanced diet should contain 12% of proteins, 25% of fats and 63% of carbohydrates. If a child needs 2600 calories in his food daily, find in calories the amount of each of these in his daily food intake.
Answer:
Amount of proteins = 12% of 2600
= 26 × 12
= 312 calories
Amount of fats = 25% of 2600
= 26 × 25
= 650 calories
Amount of carbohydrates = 63% of 2600
= 26 × 63
= 1638 calories
Question 22.
Gunpowder contains 75% nitre and 10% sulphur. Find the amount of gunpowder which carries 9 kg nitre. What amount of gunpowder would contain 2.5 kg sulphur?
Answer:
Let the amount of gunpowder which carries 9 kg nitre = Z
∴ 75% of Z = 9 kg
⇒ Z × 75/100 = 9
⇒ Z = 9 × 100/75
⇒ Z = 9 × 4/3
⇒ Z = 12 kg
Now,
Let the amount of gunpowder which carries 2.5 kg sulphur = K
∴ 10% of K = 2.5 kg
⇒ K × 10/100 = 2.5
⇒ K = 2.5 × 100/10
⇒ K = 2.5 × 10
⇒ K = 25 kg
Question 23.
Divide Rs. 7000 among A, B and C such that A gets 50% of what B gets and B gets 50% of what C gets.
Answer:
Let the amount of money gets by C = Rs. Z
∴ Amount of money B gets = (50% of Rs.Z)
∴ Amount of money A gets = (50% of B)
= (25% of Rs.Z)
Now,
Z + (50% of Rs.Z) + (25% of Rs.Z) = RS.7000
⇒ Z + (Z × 50/100) + (Z × 25/100) = 7000
⇒ Z + 50 Z/100 + 25 Z/100 = 7000
⇒ 175 Z/100 = 7000
⇒ Z = 7000 × 100/175
⇒ Z = 7000 × 4/7
⇒ Z = 4000
∴ C gets = Rs.4000
∴ Amount of money B gets = (50% of Rs.Z)
= (50% of Rs.4000)
= (Rs.4000 × 50/100)
= Rs.2000
∴ Amount of money A gets = (25% of Rs.Z)
= (25% of Rs.4000)
= (Rs.4000 × 25/100)
= Rs.1000
Question 24.
Find the percentage of pure gold in 22-carat gold, if 24-carat gold is 100% pure.
Answer:
22-carat gold contains 22 parts out of 24 parts.
∴ Percentage of pure gold in 22-carat gold 
Hence, 22-carat gold contains 
of pure gold.
Question 25.
The salary of an officer is increased by 25%. By what per cent should the new salary be decreased to restore the original salary?
Answer:
Let the original salary = Rs.100
Then,
After increment of 25% = 100 (1 + 25/100)
= 100 (125/100)
= Rs.125
Now,
To restore the original salary,
Let the new salary decreased by Z%
∴ 125(1 – Z/100) = 100
⇒ (1 – Z/100) = 100/125
⇒ (1 – Z/100) = 4/5
⇒ Z/100 = 1/5 [1 – 4/5 = 1/5]
⇒ Z = 100/5
⇒ Z = 20%
Exercise 9b
Question 1.Choose the correct answer:
A.
B.
C.
D. 
Answer:
3/5 = (3/5 × 100) %
= (3 × 20) %
= 60%
Question 2.
when expressed as a percentage, is
A.
B.
C.
D.
Answer:
0.8% = 0.8/100
= 0.008
Question 3.
when expressed as a percentage, is
A.
B.
C.
D.
Answer:
6 : 5 = 6/5
= (6/5 × 100) % [100% = 1]
= (6 × 20) %
= 120 %
Question 4.
of a number is 9. The number is
A.
B.
C.
D.
Answer:
Let number = Z
Then,
5% of Z = 9
⇒ 5/100 × Z = 9
⇒ 5 Z = 900
⇒ Z = 180
Question 5.
What per cent of 90 is 120?
A.
B.
C.
D. none of these
Answer:
Let Z% of 90 is 120
∴ Z/100 × 90 = 120
⇒ 90 Z = 120 × 100
⇒ Z = 12000/90
⇒ Z = 400/3
⇒ Z = 
Question 6.
What per cent of 10 kg 250 g?
A.
B.
C.
D.
Answer:
10 kg = 10 × 1000
= 10000 g
Let Z% of 1000 is 250
∴ Z/100 × 10000 = 250
⇒ 100 Z = 250
⇒ Z = 250/100
⇒ Z = 2.5%
Question 7.
of
A.
B.
C.
D.
Answer:
Let, 40% of Z = 240
⇒ 40/100 × Z = 240
⇒ Z = 240 × 100/40
⇒ Z = 6 × 100 [40 × 6 = 240]
⇒ Z = 600
Question 8.
?% of 400 = 60
A.
B.
C.
D.
Answer:
Let, Z% of 400 = 600
⇒ Z/100 × 400 = 60
⇒ 4 Z = 60
⇒ Z = 60/4
⇒ Z = 15
Question 9.
(180% of ?)
A.
B.
C.
D.
Answer:
Let (180% of Z) 
∴ (180/100 × Z)
⇒ (18/10 × Z) = 504 × 2
⇒ Z = 504 × 2 × 10/18
⇒ Z = 504 × 10/9
⇒ Z = 560
Question 10.
20% or Rs. 800 = ?
A.
B.
C.
D. none of these
Answer:
20% of Rs.800 = 20/100 × 800
= 20 × 8
= 160
Question 11.
In an examination, Nitin gets 98 marks. This amounts to 56% of the maximum marks.
What are the maximum marks?
A. 75
B. 150
C. 175
D. 225
Answer:
Let the maximum marks = Z
∴ 56% of Z = 98
⇒ Z × 56/100 = 98
⇒ Z = 98 × 100/56
⇒ Z = 7 × 100/4
⇒ Z = 175
Question 12.
A number is first increased by 10% and then reduced by 10%. The number
A. does not change
B. decrease by 1%
C. increased by 1%
D. none of these
Answer:
Let the number = Z
10% increased by number = Z (1 + 10/100)
= 11Z/10
Now,
10% decreased by number = 11Z/10 (1 - 10/100)
= (11Z/10) (90/100)
= 99Z/100
∴ difference = Z – 99Z/100
= Z/100
Percentage of decreases = Z/100 × 1/Z × 100
= 1%
Question 13.
A period of 4 hours 30 min is what per cent of a day?
A.
B.
C.
D.
Answer:
4 hours 30 min = (4 × 60) + 30
= 240 + 30
= 270 min
24 hours = 24 × 60
= 1440 min
Now,
Percentage = (270/1440 × 100) %
= (3/16 × 100) %
= (3/4 × 25) %
= (75/4) %
= 
Question 14.
In an examination, 65% of the total examines passed. If the number of failures is 420, the total number of examines is
A.
B.
C.
D.
Answer:
Let the total number of examines = Z
Percentage of examines failed = (100 – 65) % = 35%
∴ 35% of Z = 420
⇒ Z × 35/100 = 420
⇒ Z = 420 × 100/35
⇒ Z = 12 × 100
⇒ Z = 1200
Question 15.
A number exceeds 20% of itself by 40. The number is
A. 50
B. 60
C. 80
D. 320
Answer:
Let the number = Z
∴ 20% of Z + 40 = Z
⇒ (Z × 20/100) + 40 = Z
⇒ Z/5 + 40 = Z
⇒ Z – Z/5 = 40
⇒ 4Z/5 = 40
⇒ Z = 40 × 5/4
⇒ Z = 50
Question 16.
A number decreased by
of itself by 87. The number is
A. 58
B. 110
C. 120
D. 135
Answer:
Let the number = Z
∴ Z - (
of Z) = 87
⇒ Z - (Z × 55/2 × 1/100) = 87
⇒ Z - (Z × 11/2 × 1/20) = 87
⇒ Z- (11Z/40) = 87
⇒ 29Z/40 = 87
⇒ 29Z/40 = 87
⇒ Z = 87 × 40/29
⇒ Z = 120
Question 17.
is what per cent of
A.
B.
C.
D.
Answer:
Percentage = (0.05/20 × 100) %
= (0.05 × 5) %
= 0.25%
Question 18.
One-third of 1206 is what per cent of
A.
B.
C.
D.
Answer:
Percentage = {(1/3 × 1206) × (1/134) × 100} %
= {402 × 1/134 × 100} %
= {3 × 100} %
= 300%
Question 19.
x% of y is y% of
A.
B.
C.
D.
Answer:
Let x% of y is y% of Z
∴ x/100 × y = y/100 × Z
⇒ x y/100 = y/100 × Z
⇒ Z = x y/100 × 100/y
⇒ Z = x
Question 20.
What per cent of
is
A.
B.
C.
D.
Answer:
Percentage = {(1/35)/(2/7) × 100} %
= {1/35 × 7/2 × 100} %
= {1/5 × 1/2 × 100} %
= {1/5 × 50} %
= 10%
Cce Test Paper-9
Question 1.Express:
24% as a fraction;
Answer:
24% means, 24 divided by 100.
So, 24% = 24/100
= 6/25
Question 2.
Express:
105% as a decimal;
Answer:
105% means, 105 divided by 100.
So, 105% = 105/100
= 1.05
Question 3.
Express:
4 : 5 as a percentage;
Answer:
4 : 5 = 4 /5
= (4 /5 x 100) % [Because 100% = 1]
= 80%
Question 4.
Express:
56% as a ratio.
Answer:
56% means, 56 divided by 100.
So, 56% = 56/100
= 14/25
= 14:25
Question 5.
If 34% of a number is 85, find the number.
Answer:
Let the number = Z
∴ 34% of Z = 85
⇒ 34/100 x Z = 85
⇒ Z = 85 x 100/34
⇒ Z = 5 x 100/2
⇒ Z = 250
Question 6.
The value of a machine depreciates every year by 10%. If the present value of the machine is Rs.54000, what was its value last year?
Answer:
Let the value of the machine last year = Z
∴ Present value of the machine = (100 – 10) % of Rs.Z
⇒ 54000 = 90% of Z
⇒ 54000 = Z x 90/100
⇒ Z = 54000 x 100/90
⇒ Z = 600 x 100
⇒ Z = 60000
Question 7.
An alloy contains 30% copper, 42% nickel and rest zinc. Find the mass of zinc in 1 kg of alloy.
Answer:
Given,
Percentage of copper = 30%
Percentage of nickel = 42%
∴ Percentage of zinc = {100 – (30 + 42)} %
= 28 %
Now,
Mass of zinc in 1 kg of the alloy = (28 × 1/100) kg
= 0.28 kg
= 0.28 × 1000 g
= 280 g
Question 8.
In a class, 60% of the total number of students are boys and there are 14 girls. How many students are there in the class?
Answer:
Let the total number of students = Z
Percentage of girls = (100 – 60) % = 40%
Now,
Number of girls = 40% of Z
⇒ 14 = Z × 40/100
⇒ Z = 14 × 100/40
⇒ Z = 14 × 5/2
⇒ Z = 35
Question 9.
Which is largest in
and
Answer:
= (25 /3) %
= (25 /3 x 1 /100)
= 8.33 /100
= 0.08 _____ (i)
= 0.16 ______ (ii)
0.15 _____ (iii)
From equation (i), (ii) and (iii),
0.16 > 0.15 > 0.08
Question 10.
What per cent of
is
A. 2.5%
B. 5%
C. 7.5%
D. 10%
Answer:
Percentage = {(1/45)/(2/9) × 100} %
= {1/45 × 9/2 × 100} %
= {1/5 × 1/2 × 100} %
= {1/5 × 50} %
= 10%
Question 11.
A number decreased by 30% gives 84. The number is
A. 90
B. 110
C. 120
D. 135
Answer:
Let the number = Z
∴ Z – (30% of Z) = 84
⇒ Z – (Z × 30/100) = 84
⇒ Z – 30 Z/100 = 84
⇒ 70 Z/100 = 84
⇒ Z = 84 × 100/70
⇒ Z = 12 × 10
⇒ Z = 120
Question 12.
(?)% of 320 is 48?
A. 25%
B. 15%
C. 14%
D. 9%
Answer:
Percentage = (48/320 × 100) %
= (48/32 × 10) %
= (3/2 × 10) %
= 15%
Question 13.
What per cent of 45 is 54?
A.
%
B. 104%
C. 108%
D. 120%
Answer:
Percentage = (54/45 × 100) %
= (54/9 × 20) %
= (6 × 20) %
= 120%
Question 14.
A number exceeds 25% of itself by 60. The number is
A. 75
B. 45
C. 80
D. 65
Answer:
Let the number = Z
∴ 25% of Z + 60 = Z
⇒ (Z × 25/100) + 60 = Z
⇒ Z/4 + 60 = Z
⇒ Z – Z/4 = 60
⇒ 3Z/4 = 60
⇒ Z = 60 × 4/3
⇒ Z = 80
Question 15.
5% of which number is 12?
A. 120
B. 180
C. 240
D. 320
Answer:
Let the number = Z
∴ 5% of Z = 12
⇒ Z × 5/100 = 12
⇒ Z = 12 × 100/5
⇒ Z = 12 × 20
⇒ Z = 240
Question 16.
Fill in the blanks.
(i)
% of Rs.1200 = ……..
(ii) 240 mL is……% of 3 L.
(iii) If
% of 35 is 42, then=……..
(iv)
(v) 120 = (……)% of 80.
Answer:
(i) 90
% of Rs.1200 = (15/2) % of Rs.1200
= 15/2 × 1/100 × 1200
= 15/2 × 12
= 90
∴ Rs.90
(ii) 8
240 mL = (240/1000) L
Now,
Percentage = (240/1000 × 1/3 × 100) %
= (240/10 × 1/3) %
= (80/10) %
= 8%
(iii) 120
X% of 35 = 42
⇒ 35 × X/100 = 42
⇒ 35X/100 = 42
⇒ X = 42 × 100/35
⇒ X = 6 × 100/5
⇒ X = 120
(iv) 240
12/5 = (12/5 × 100) %
= (12 × 20) %
= 240%
(v) 150
Let the number = Z
∴ 120 = Z% of 80
⇒ 120 = 80 × Z/100
⇒ Z = 120 × 100/80
⇒ Z = 120 × 5/4
⇒ Z = 150
Question 17.
Write ‘T’ for true and ‘F’ for false for each of the following:
(i) 6% of 8 is 48.
(ii) 6 : 5 = 30%.
(iii)
= 60%.
(iv) 6 hours = 25% of a day.
Answer:
(i) False
6% of 8 = 8 × 6/100
= 48/100
= 0.48
(ii) False
6:5 = 6/5
= (6/5 × 100) %
= (6 × 20) %
= 120%
(iii) True
3/5 = 3/5
= (3/5 × 100) %
= (3 × 20) %
= 60%
(iv) True
1 day = 24 hours
6 hours = (6/24 × 100) %
= (1/4 × 100) %
= 25%