Class 8 Mathematics MCQ Direct And Inverse Proportions

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NCERT Class 8 Mathematics MCQ
Direct And Inverse Proportions with Answers

Question :10 metres of cloth cost Rs 1000. What will 4 metres cost ?
(a) Rs 400
(b) Rs 800
(c) Rs 200
(d) Rs 100.

Show Answer :

Answer : (a) Rs 400
Explanation:
$\frac{10}{1000}$ = $\frac{4}{?}$ ⇒ ? = 400

Question :15 books weigh 6 kg. What will 6 books weigh ?
(a) 1.2 kg
(b) 2.4 kg
(c) 3.8 kg
(d) 3 kg.

Show Answer :

Answer : (b) 2.4 kg
Explanation:
$\frac{15}{6}$ = $\frac{6}{?}$ ⇒ ? = 2.4

Question :A horse eats 18 kg of com in 12 days ? How much does he eat in 9 days ?
(a) 11.5 kg
(b) 12.5 kg
(c) 13.5 kg
(d) 14.5 kg.

Show Answer :

Answer : (c) 13.5 kg
Explanation:
$\frac{12}{18}$ = $\frac{9}{?}$ ⇒ ? = $\frac{18×9}{12}$ = 13.5

Question :8 g of sandal wood cost Rs 40. What will 10 g cost ?
(a) Rs 30
(b) Rs 36
(c) Rs 48
(d) Rs 50.

Show Answer :

Answer : (d) Rs 50.
Explanation:
$\frac{8}{10}$ = $\frac{10}{?}$ ⇒ ? = 50

Question :20 trucks can hold 150 metric tonnes. How much will 12 trucks hold ?
(a) 80 metric tonnes
(b) 90 metric tonnes
(c) 60 metric tonnes
(d) 40 metric tonnes.

Show Answer :

Answer : (b) 90 metric tonnes
Explanation:
$\frac{20}{150}$ = $\frac{12}{?}$ ⇒ ? = 90

Question :120 copies of a book cost Rs 600. What will 400 copies cost ?
(a) Rs 1000
(b) Rs 2000
(c) Rs 3000
(d) Rs 2400.

Show Answer :

Answer : (b) Rs 2000
Explanation:
$\frac{120}{600}$ = $\frac{400}{?}$ ⇒ ? = 2000

Question :The rent of 7 hectares is Rs 875. What is the rent of 16 hectares ?
(a) Rs 2000
(b) Rs 1500
(c) Rs 1600
(d) Rs 1200.

Show Answer :

Answer : (a) Rs 2000
Explanation:
$\frac{7}{875}$ = $\frac{16}{?}$ ⇒ ? = $\frac{875×16}{7}$ = 2000

Question :A boy runs 1 km in 10 minutes. How long will he take to ran 600 m ?
(a) 2 minutes
(b) 3 minutes
(c) 4 minutes
(d) 6 minutes.

Show Answer :

Answer : (d) 6 minutes.
Explanation:
$\frac{1000}{10}$ = $\frac{600}{?}$ ⇒ ? = 6

Question :A shot travels 90 m in 1 second. How long will it take to go 225 m ?
(a) 2 seconds
(b) 2.5 seconds
(c) 4 seconds
(d) 3.5 seconds.

Show Answer :

Answer : (b) 2.5 seconds
Explanation:
$\frac{90}{1}$ = $\frac{225}{?}$ ⇒ ? = 2.5

Question :3 knives cost Rs 63. What will 17 knives cost ?
(a) Rs 357
(b) Rs 375
(c) Rs 537
(d) Rs 573.

Show Answer :

Answer : (a) Rs 357
Explanation:
$\frac{3}{63}$ = $\frac{17}{?}$ ⇒ ? = 357

Question :15 men can mow 40 hectares of land in 1 day. How much will 6 men mow in 1 day ?
(a) 16 hectares
(b) 12 hectares
(c) 20 hectares
(d) 24 hectares.

Show Answer :

Answer : (a) 16 hectares
Explanation:
$\frac{15}{40}$ = $\frac{6}{?}$ ⇒ ? = $\frac{40×6}{15}$ = 16

Question :A man walks 20 km in 5 hours. How long would he take in walking 32 km ?
(a) 3 hours
(b) 4 hours
(c) 6 hours
(d) 8 hours.

Show Answer :

Answer : (d) 8 hours.
Explanation:
$\frac{20}{5}$ = $\frac{32}{?}$ ⇒ ? = 8

Question :What is the cost of 50 sticks at Rs 24 per score ?
(a) Rs 30
(b) Rs 40
(c) Rs 50
(d) Rs 60.

Show Answer :

Answer : (d) Rs 60.
Explanation:
$\frac{20}{24}$ = $\frac{50}{?}$ ⇒ ? = 60

Question :A train travels 60 km in 1 hour. How long will it take to go 150 km ?
(a) 2 hours
(b) 3 hours
(c) 2.5 hours
(d) 4 hours.

Show Answer :

Answer : (c) 2.5 hours
Explanation:
$\frac{60}{1}$ = $\frac{150}{?}$ ⇒ ? = 2.5

Question :If 3 quintals of coal cost Rs 6000, what is the cost of 120 kg ?
(a) Rs 1200
(b) Rs 2400
(c) Rs 3600
(d) Rs 4800.

Show Answer :

Answer : (b) Rs 2400
Explanation:
$\frac{300}{6000}$ = $\frac{120}{?}$ ⇒ ? = 2400

Question :If 20 cows eat as much as 15 oxen, how many cows will eat at much as 36 oxen ?
(a) 40
(b) 44
(c) 45
(d) 48

Show Answer :

Answer : (d) 48
Explanation:
$\frac{15}{20}$ = $\frac{36}{?}$ ⇒ ? = $\frac{20×36}{15}$ = 48

Question :The fare for a journey of 40 km is Rs 25. How much can be travelled for Rs40 ?
(a) 32 km
(b) 64 km
(c) 50 km
(d) 60 km.

Show Answer :

Answer : (b) 64 km
Explanation:
$\frac{25}{40}$ = $\frac{40}{?}$ ⇒ ? = $\frac{40×40}{25}$ = 64

Question :Apala types 200 words in half an hour. How many words will she type in 12 minutes ?
(a) 80
(b) 50
(c) 100
(d) 60.

Show Answer :

Answer : (a) 80
Explanation:
$\frac{30}{200}$ = $\frac{12}{?}$ ⇒ ? = 80

Question :A labourer is paid Rs 400 for 2 days work. If he works for 5 days, how much will he get ?
(a) Rs 1000
(b) Rs 800
(c) Rs 750
(d) Rs 900.

Show Answer :

Answer : (a) Rs 1000
Explanation:
$\frac{2}{400}$ = $\frac{5}{?}$ ⇒ ? = 1000

Question :A machine in a soft drink factory fills 600 bottles in 5 hours. How many bottles will it fill in 2 hours ?
(a) 120
(b) 180
(c) 150
(d) 240.

Show Answer :

Answer : (d) 240
Explanation:
$\frac{5}{600}$ = $\frac{2}{?}$ ⇒ ? = 240

Question :If 8 men can do a piece of work in 20 days, in how many days could 20 men do the same work ?
(a) 6 days
(b) 8 days
(c) 4 days
(d) 10 days.

Show Answer :

Answer : (b) 8 days
Explanation:
8 × 20 = 20 × ? ⇒ ? = 8.

Question :If an amount of food last for 40 days for 120 men, how long will it last for 80 men at the same rate ?
(a) 50 days
(b) 60 days
(c) 80 days
(d) 100 days.

Show Answer :

Answer : (b) 60 days
Explanation:
40 × 120 = 80 × ? ⇒ ? = 60.

Question :If 18 women can reap a field in 7 days, in what time can 6 women reap the same field ?
(a) 15 days
(b) 21 days
(c) 30 days
(d) 36 days.

Show Answer :

Answer : (b) 21 days
Explanation:
18 × 7 = 6 × ? ⇒ ? = 21.

Question :10 men can dig a trench in 15 days. How long will 3 men take ?
(a) 50 days
(b) 60 days
(c) 100 days
(d) 75 days.

Show Answer :

Answer : (a) 50 days
Explanation:
10 × 15 = 3 × ? ⇒ ? = 50.

Question :3 lambs finish eating turnips in 8 days. In how many days will 2 lambs finish them ?
(a) 6
(b) 8
(c) 10
(d) 12.

Show Answer :

Answer : (d) 12
Explanation:
3 × 8 = 2 × ? ⇒ ? = 12.

Question :6 pipes are required to fill a tank in 1 hour. How long will it take if only 5 pipes of the same type are used ?
(a) 75 minutes
(b) 72 minutes
(c) 80 minutes
(d) 90 minutes.

Show Answer :

Answer : (b) 72 minutes
Explanation:
6 × 60 = 5 × ? ⇒ ? = 72 minutes.

Question :40 cows can graze a field in 16 days. How many cows will graze the same field in 10 days ?
(a) 60
(b) 64
(c) 80
(d) 75.

Show Answer :

Answer : (b) 64
Explanation:
40 × 16 = ? × 10 ⇒ ? = 64.

Question :If x = ky and when y = 4, x = 8 then k =
(a) 1
(b) 2
(c) 3
(d) 4.

Show Answer :

Answer : (b) 2
Explanation:
8 = 4k ⇒ k = 2.

Question :The constant of variation, if x ∝ y, from the following table is

X	6	12	15	21
Y	2	4	5	7

(a) 1
(b) 2
(c) 3
(d) 4.

Show Answer :

Answer : (c) 3
Explanation:
2 × 3 = 6, 4 × 3 = 12,
5 × 3 = 15, 7 × 3 = 21.

Question :x and y vary inversely with each other. If x – 15 when y = 6, then the value of x when y = 15 is
(a) 2
(b) 4
(c) 5
(d) 6.

Show Answer :

Answer : (d) 6
Explanation:
15 × 6 = ? × 15 ⇒ ? = 6.

Question :If x = 20 and y = 40, then x and y are:
(a) Directly proportional
(b) Inversely proportional
(c) Neither directly nor inversely proportional
(d) Cannot be determined

Show Answer :

Answer : (a) Directly proportional
Explanation:
x = 20 and y = 40
Clearly, 40 = 2 × 20
y = 2x
y ∝ x, where 2 is the proportionality constant.

Question :If x = 15 and y = 1/30, then x and y are:
(a) Directly proportional
(b) Inversely proportional
(c) Neither directly nor inversely proportional
(d) Cannot be determined

Show Answer :

Answer : (a) Directly proportional
Explanation:
x = 15, y = 1/30
1/30 = 1/(2 × 15)
y = 1/2x
Hence, y ∝ 1/x, where 1/2 is the proportionality constant.

Question :If x and y are directly proportional, then which of the following is correct?
(a) x + y = constant
(b) x – y = constant
(c) x y = constant = constant
(d) x / y = constant = constant

Show Answer :

Answer : (d) x/y = constant
Explanation:
x ∝ y
x = ky
k = x/y, where k is a constant.

Question :If x and y are inversely proportional, then:
(a) x + y = constant
(b) x – y = constant
(c) x y = constant = constant
(d) x / y = constant = constant

Show Answer :

Answer : (c) xy = constant
Explanation:
x ∝ 1/y
x = k/y
xy = k
Where k is a constant.

Question :If x ∝ y and x₁= 5, y₁ = 210 and x₂ = 2, then find y₂ ?
(a) 200
(b) 84
(c) 99
(d) 70

Show Answer :

Answer : (b) 84
Explanation:
x ∝ y
x = ky
x/y = k
x₁/y₁ = x₂/y₂
5/210 = 2/y₂
y₂ = 84

Question :If the weight of 12 sheets of thick paper is 40 grams, how many sheets of the same paper would weigh 2500 grams?
(a) 750
(b) 800
(c) 850
(d) 950

Show Answer :

Answer : (a) 750
Explanation:
For 12 sheets, weight of paper is 40 grams
Let number of sheets for 2500 is x.
Using direct proportion concept:
12/40 = x/2500
x = (12 × 2500)/40
x = 750

Question :The scale of a map is given as 1 : 300. Two cities are 4 km apart on the map. The actual distance between them is:
(a) 1000 km
(b) 1100 km
(c) 1200 km
(d) 1300 km

Show Answer :

Answer : (c) 1200 km
Explanation:
1 : 300 = x : y
1/300 = 4/y
y = 4 x 300 = 1200
Hence, the distance between the two cities is 1200 km.

Question :If x and y are inversely proportional, then which one is true?
(a) x₁/y₁ = x₂/y₂
(b) x₁/x₂ = y₁/y₂
(c) x₁/x₂ = y₂/y₁
(d) x₁.x₂ = y₁.y₂

Show Answer :

Answer : (c) x₁/x₂ = y₂/y₁
Explanation:
x ∝1/y
x = k (1/y)
xy = k
x₁y₁=x₂y₂
x₁/x₂=y₂/y₁

Question :6 pipes are required to fill a tank in 1 hour 20 minutes. If we use 5 such types of pipes, how much time it will take to fill the tank?
(a) 120 minutes
(b) 96 minutes
(c) 80 minutes
(d) 85 minutes

Show Answer :

Answer : (b) 96 minutes
Explanation:
For 6 pipes, it takes 1 hour 20 minutes
1 hour 20 minutes = 60 + 20 = 80 minutes
For 5 pipes, let the time taken be x.
This is inverse proportion case:
80 × 6 = x × 5
x = 480/5 = 96

Question :If 12 workers can build a wall in 50 hours, how many workers will be required to do the same work in 40 hours?
(a) 10
(b) 13
(c) 14
(d) 15

Show Answer :

Answer : (d) 15
Explanation:
12 × 50 = x × 40
x = (12×50)/40 = 15

Question : If the cost of 27 bags of paddy is Rs.9450, what is the cost of 36 bags of paddy?

(a) Rs.12000
(b) Rs.12600
(c) Rs.16200
(d) Rs.10620

Show Answer :

Answer :(b) Rs.12600

Question : 15 books weigh 6 kg. What will 6 books weigh ?

(a) 1.2 kg
(b) 2.4 kg
(c) 3.8 kg
(d) 3 kg.

Show Answer :

Answer :(b) 2.4 kg

Question : A boy runs 1 km in 5 minutes. How long will he take to run 600 m?

(a) 2 minutes
(b) 3 minutes
(c) 4 minutes
(d) 6 minutes

Show Answer :

Answer :(c) 4 minutes

Question : 72 books are packed in 4 cartons of the same size. How many cartons are required for 360 books?

(a) 22
(b) 18
(c) 20
(d) None of these

Show Answer :

Answer :(c) 20

Question : The scale of a map is 1:3×107 Two cities are 5 cm apart on the map. Find the actual distance between them in kilometres.

(a) 1500 km
(b) 1000 km
(c) 1100 km
(d) 2000 km

Show Answer :

Answer :(a) 1500 km

Question : 8 g of sandal wood cost Rs 40. What will 10 g cost ?

(a) Rs 30
(b) Rs 36
(c) Rs 48
(d) Rs 50.

Show Answer :

Answer :(d) Rs 50.

Question : If 3 quintals of coal cost Rs 6000, What is the cost of 120 kg?

(a) Rs 1200
(b) Rs 2400
(c) Rs 3600
(d) Rs 4800

Show Answer :

Answer :(b) Rs 2400

Question : 6 pipes are required to fill a tank in 1 hour 20 minutes. How long will it take if only 5 pipes of the same type are used?

(a) 56 minutes
(b) 72 minutes
(c) 96 minutes
(d) 80 minutes

Show Answer :

Answer :(c) 96 minutes

Question : The price of 357 mangoes is Rs.1517.25. What will be the approximate price of 49 dozens of such mangoes?

(a) Rs.3000
(b) Rs.3500
(c) Rs.4000
(d) Rs.2500

Show Answer :

Answer :(a) Rs.3000

Question : The rent of 7 hectares is Rs 875. What is the rent of 16 hectares ?

(a) Rs 2000
(b) Rs 1500
(c) Rs 1600
(d) Rs 1200.

Show Answer :

Answer :(a) Rs 2000

Question : If x and y vary inversely. Then using the following table, find x if y = 10. x = 15, y = 90

(a) 100
(b) 135
(c) 400
(d) 200

Show Answer :

Answer :(b) 135

Question : An electric pole, 14 metres high, casts a shadow of 10 metres. Find the height of a tree that casts a shadow of 15 metres under similar conditions.

(a) 21 metres
(b) 30 metres
(c) 25 metres
(d) None of these

Show Answer :

Answer :(a) 21 metres

Question : There is enough food to last for 40 people for 10 days. If 10 more people join them, the food will last for

(a) 10 days
(b) 12 days
(c) 8 days
(d) None of these

Show Answer :

Answer :(c) 8 days

Question : A shot travels 90 m in 1 second. How long will it take to go 225 m ?

(a) 2 seconds
(b) 2.5 seconds
(c) 4 seconds
(d) 3.5 seconds.

Show Answer :

Answer :(b) 2.5 seconds

Question : x varies inversely as square of y. Given that y = 3 for x = 1.find the value of x for y = 4.

(a) 3
(b) 9
(c) 1/3
(d) 9/16

Show Answer :

Answer :(d) 9/16

Question : A journey by bus takes 45 minutes at 40 km/hour. How fast must a car go to undertake the same journey in 25 minutes?
(a) 36 km/h
(b) 48 km/h
(c) 72 km/h
(d) None of these

Show Answer :

Answer :(c) 72 km/h

Question : 15 men can mow 40 hectares of land in 1 day. How much will 6 men mow in 1 day ?

(a) 16 hectares
(b) 12 hectares
(c) 20 hectares
(d) 24 hectares.

Show Answer :

Answer :(a) 16 hectares

Question : If 3 men or 6 women can do a piece of work in 16 days, in how many days can 12 men and 8 women do the same piece of work?

(a) 4 days
(b) 5 days
(c) 3 days
(d) 2 days

Show Answer :

Answer :(c) 3 days

Question : 8 g of sandal wood cost Rs 40. What will 10 g cost ?

(a) Rs 30
(b) Rs 36
(c) Rs 48
(d) Rs 50

Show Answer :

Answer :(d) Rs 50

Question : What is the cost of 50 sticks at Rs 24 per score ?

(a) Rs 30
(b) Rs 40
(c) Rs 50
(d) Rs 60.

Show Answer :

Answer :(d) Rs 60.

Question :A mixture of paint is prepared by mixing 1 part of red pigments with 8 parts of base. How many parts of base will be used in mixture by mixing 7 part of red pigment?
(a) 70
(b) 56
(c) 63
(d) 49

Show Answer :

Answer : (b) 56

Question :If 3 men or 6 women can do a piece of work in 16 days, in how many days can 12 men and 8 women do the same piece of work?
(a) 4 days
(b) 5 days
(c) 3 days
(d) 2 days

Show Answer :

Answer : (c) 3 days

Question :If the cost of 27 bags of paddy is Rs.9450, what is the cost of 36 bags of paddy?
(a) Rs.12000
(b) Rs.12600
(c) Rs.16200
(d) Rs.10620

Show Answer :

Answer : (b) Rs.12600

Question :Raju earns Rs 1440, if he works for 12 days. If he works for 30 days, he will earn
(a) Rs 2400
(b) Rs 3600
(c) Rs 4800
(d) None of these

Show Answer :

Answer : (b) Rs 3600

Question :The scale of a map is 1:3×10⁷ Two cities are 5 cm apart on the map. Find the actual distance between them in kilometres.
(a) 1500 km
(b) 1000 km
(c) 1100 km
(d) 2000 km

Show Answer :

Answer : (a) 1500 km

Question :An electric pole, 14 metres high, casts a shadow of 10 metres. Find the height of a tree that casts a shadow of 15 metres under similar conditions.
(a) 21 metres
(b) 30 metres
(c) 25 metres
(d) None of these

Show Answer :

Answer : (a) 21 metres

Question :A boy runs 1 km in 10 minutes. How long will he take to ran 600 m ?
(a) 2 minutes
(b) 3 minutes
(c) 4 minutes
(d) 6 minutes

Show Answer :

Answer : (d) 6 minutes

Question :A van covers 432 km with 36 litres of diesel. How much distance would it cover with 25 litres of diesel?
(a) 200 km
(b) 300 km
(c) 100 km
(d) 350 km

Show Answer :

Answer : (b) 300 km

Question :The price of 357 mangoes is Rs.1517.25. What will be the approximate price of 49 dozens of such mangoes?
(a) Rs.3000
(b) Rs.3500
(c) Rs.4000
(d) Rs.2500

Show Answer :

Answer : (a) Rs.3000

Question :72 books are packed in 4 cartons of the same size. How many cartons are required for 360 books?
(a) 22
(b) 18
(c) 20
(d) None of these

Show Answer :

Answer : (c) 20

Question :A garrison of 500 persons had provisions for 27 days. After 3 days a reinforcement of 300 persons arrived. For how many more days will the remaining food last now?
(a) 12 days
(b) 14 days
(c) 16 days
(d) 15 days

Show Answer :

Answer : (d) 15 days

Question :Two quantities x and y are said to be in ___________ if they increase (decrease) together in such a manner that the ratio of their corresponding values remains constant.
(a) inverse proportion
(b) mix proportion
(c) direct proportion
(d) None of these

Show Answer :

Answer : (c) direct proportion

Question :There is enough food to last for 40 people for 10 days. If 10 more people join them, the food will last for
(a) 10 days
(b) 12 days
(c) 8 days
(d) None of these

Show Answer :

Answer : (c) 8 days

Question :36 men can complete a piece of work in 18 days. In how many days will 27 men complete the same work ?
(a) 24 days
(b) 28 days
(c) 34 days
(d) 35 days

Show Answer :

Answer : (a) 24 days

Question :x varies inversely as square of y. Given that y = 3 for x = 1.find the value of x for y = 4.
(a) 3
(b) 9
(c) $\frac { 1 }{ 3 }$
(d) $\frac { 9 }{ 16 }$

Show Answer :

Answer : (d) $\frac { 9 }{ 16 }$

Question :A journey by bus takes 45 minutes at 40 km/hour. How fast must a car go to undertake the same journey in 25 minutes?
(a) 36 km/h
(b) 48 km/h
(c) 72 km/h
(d) None of these

Show Answer :

Answer : (c) 72 km/h

Question :A can do a certain work in the same time in which B and C together can do it. If A and B together could do it in 10 days and C alone in 50 days, then B alone could do it in:
(a) 15 days
(b) 20 days
(c) 25 days
(d) 30 days

Show Answer :

Answer : (c) 25 days

Question :The cost of 5 metres of a particular quality of cloth is Rs 210. Find the cost of 2 metres of cloth of the same type.
(a) Rs 100
(b) Rs 84
(c) Rs 90
(d) Rs 60

Show Answer :

Answer : (b) Rs 84

Question :120 copies of a book cost Rs 600. What will 400 copies cost ?
(a) Rs 1000
(b) Rs 2000
(c) Rs 3000
(d) Rs 2400

Show Answer :

Answer : (b) Rs 2000

Question :6 pipes are required to fill a tank in 1 hour 20 minutes. How long will it take if only 5 pipes of the same type are used?
(a) 56 minutes
(b) 72 minutes
(c) 96 minutes
(d) 80 minutes

Show Answer :

Answer : (c) 96 minutes

Question :8 g of sandal wood cost Rs 40. What will 10 g cost ?
(a) Rs 30
(b) Rs 36
(c) Rs 48
(d) Rs 50

Show Answer :

Answer : (d) Rs 50

Question :When one quantity is increased, the other quantity is also increased. This proportion is called _______
(a) Kally proportion
(b) Direct proportion
(c) Inverse proportion
(d) None of these

Show Answer :

Answer : (b) Direct proportion

Question : If x = 20 and y = 40, then x and y are:
(a) Directly proportional
(b) Inversely proportional
(c) Neither directly nor inversely proportional
(d) Cannot be determined

Show Answer :

Answer :A
Explanation: x = 20 and y = 40
Clearly, 40 = 2 x 20
y=2x
y∝x, where 2 is the proportionality constant.

Question : If x = 15 and y = 1/30, then x and y are:
(a) Directly proportional
(b) Inversely proportional
(c) Neither directly nor inversely proportional
(d) Cannot be determined

Show Answer :

Answer : B
Explanation: x = 15, y = 1/30
1/30 = 1/(2 × 15)
y = 1/2x
Hence, y ∝ 1/x, where 1/2 is the proportionality constant.

Question : If x∝y and x₁=5,y₁=210 and x₂ = 2, then find y₂?
(a) 200
(b) 84
(c) 99
(d) 70

Show Answer :

Answer :B
Explanation: x∝y
x=ky
x/y=k
x₁/y₁ = x₂/y₂
5/210 = 2/y₂
y₂ = 84

Question : If the weight of 12 sheets of thick paper is 40 grams, how many sheets of the same paper would weigh 2500 grams?
(a) 750
(b) 800
(c) 850
(d) 950

Show Answer :

Answer :A
Explanation: For 12 sheets, weight of paper is 40 grams
Let number of sheets for 2500 is x.
Using direct proportion concept:
12/40 = x/2500
x=(12×2500)/40
x=750

Question : The scale of a map is given as 1:300. Two cities are 4 km apart on the map. The actual distance between them is:
(a) 1000 km
(b) 1100 km
(c) 1200 km
(d) 1300 km

Show Answer :

Answer :C
Explanation: 1:300 = x : y
1/300 = 4/y
y = 4 x 300 = 1200
Hence, the distance between the two cities is 1200 km.

Question : If x and y are inversely proportional, then which one is true?
(a) x₁/y₁ = x₂/y₂
(b) x₁/x₂ = y₁/y₂
(c) x₁/x₂ = y₂/y₁
(d) x₁.x₂ = y₁.y₂

Show Answer :

Answer :C
Explanation: x∝1/y
x=k(1/y)
xy=k
x₁y₁=x₂y₂
x₁/x₂=y₂/y₁

Question : 6 pipes are required to fill a tank in 1 hour 20 minutes. If we use 5 such types of pipes, how much time it will take to fill the tank?
(a) 120 minutes
(b) 96 minutes
(c) 80 minutes
(d) 85 minutes

Show Answer :

Answer :B
Explanation: For 6 pipes, it takes 1 hour 20 minutes
1 hour 20 minutes = 60+20 = 80 minutes
For 5 pipes, let the time taken be x.
This is inverse proportion case:
80 × 6 = x × 5
x = 480/5 = 96

Question : If 12 workers can build a wall in 50 hours, how many workers will be required to do the same work in 40 hours?
(a) 10
(b) 13
(c) 14
(d) 15

Show Answer :

Answer 😀
Explanation: 12 × 50 = x × 40
x = (12×50)/40 = 15

Question : A man walks 20 km in 5 hours. How much time it will take for him to walk 32 km?
A. 3 hours
B. 4 hours
C. 6 hours
D. 8 hours

Show Answer :

Answer : D
Solution: Man walks 20 km in → 5 hours
That means it will take more time to walk 32 km. This is the case of direct proportion.
20/5 = 32/x
x = 32/4 = 8

Question : If 300 Kg of coal cost 6000₹, then find the cost of 120 kg of coal?
A. 1200₹
B. 2400₹
C. 3200₹
D. 4200₹

Show Answer :

Answer : B
Solution:
300/6000 = 120/x
x = 2400

Question : Manvi types 200 words in 30 minutes. How many words she will type in 12 minutes?
A. 100
B. 80
C. 60
D. 50

Show Answer :

Answer : B
Solution:
30/200 = 12/x
x = 12 x 200/30
x = 80

Question : If it takes 40 days for 120 men to complete a work, how long will it take for 80 men to complete the same work?
A. 50 days
B. 60 days
C. 80 days
D. 100 days

Show Answer :

Answer : B. 60 days
40 × 120 = 80 × x
⇒ x = 60

Question : 6 pipes are required to fill a tank in 80 minutes. How long will it take if only 5 pipes of the same type are used?
A. 96 minutes
B. 102 minutes
C. 106 minutes
D. 108 minutes

Show Answer :

Answer : A. 96 minutes
80 × 6 = x × 5
x = 96

Question :If 12 labours can construct a road in 50 hours, how many labours will be required to construct the same road in 40 hours?
A. 10
B. 12
C. 14
D. 15

Show Answer :

Answer : D. 15
12 × 50 = x × 40
x = (12 × 50)/40 = 15

Question : If 100 students took 20 days to clean a garden. How many days it will take to clean the garden if 25 more students are added?
A. 10
B. 12
C. 16
D. 18

Show Answer :

Answer : C. 16
100 × 20 = 125 × x
x = 16

Question : If x = 10 and y = 20, then x and y are:
A. Directly proportional
B. Inversely proportional
C. Neither directly nor inversely proportional
D. Cannot be determined

Show Answer :

Answer : A. Directly proportional
x = 10 and y = 20
y = 2 x 10 = 2x
Y is directly proportional to x, where 2 is the proportionality constant.

Question : A car takes 18 hours to ride 720 kilometres. Time taken by the car to travel 360 kilometres is:
A. 10 hours
B. 11 hours
C. 9 hours
D. 16 hours

Show Answer :

Answer : C. 9 hours
720/18 = 360/x

Question : The perimeter of a square and its side is in:
A. Direct Proportion
B. Indirect Proportion
C. Neither direct nor indirect
D. Cannot be determined

Show Answer :

Answer : A. Direct Proportion

CBSE Class 8 Mathematics MCQ Exponents and Powers with Answers

NCERT Solutions & Download NCERT Textbooks

Rational Numbers : Exercise – 1.1	Comparing Quantities : Exercise – 8.1
Rational Numbers : Exercise – 1.2	Comparing Quantities : Exercise – 8.2
Linear Equations in One Variable : Exercise – 2.1	Comparing Quantities : Exercise – 8.3
Linear Equations in One Variable : Exercise – 2.2	Algebraic Expressions and Identities : Exercise – 9.1
Linear Equations in One Variable : Exercise – 2.3	Algebraic Expressions and Identities : Exercise – 9.2
Linear Equations in One Variable : Exercise – 2.4	Algebraic Expressions and Identities : Exercise – 9.3
Linear Equations in One Variable : Exercise – 2.5	Algebraic Expressions and Identities : Exercise – 9.4
Linear Equations in One Variable : Exercise – 2.6	Algebraic Expressions and Identities : Exercise – 9.5
Understanding Quadrilaterals : Exercise – 3.1	Visualising Solid Shapes : Exercise – 10.1
Understanding Quadrilaterals : Exercise – 3.2	Visualising Solid Shapes : Exercise – 10.2
Understanding Quadrilaterals : Exercise – 3.3	Mensuration : Exercise – 11.1
Understanding Quadrilaterals : Exercise – 3.4	Mensuration : Exercise – 11.2
Practical Geometry : Exercise – 4.1	Mensuration : Exercise – 11.3
Practical Geometry : Exercise – 4.2	Mensuration : Exercise – 11.4
Practical Geometry : Exercise – 4.3	Exponents and Powers : Exercise – 12.1
Practical Geometry : Exercise – 4.4	Exponents and Powers : Exercise – 12.2
Practical Geometry : Exercise – 4.5	Direct and Inverse Proportions : Exercise – 13.1
Data Handling : Exercise – 5.1	Direct and Inverse Proportions : Exercise – 13.2
Data Handling : Exercise – 5.2	Factorisation : Exercise – 14.1
Data Handling : Exercise – 5.3	Factorisation : Exercise – 14.2
Squares and Square Roots : Exercise – 6.1	Factorisation : Exercise – 14.3
Squares and Square Roots : Exercise – 6.2	Factorisation : Exercise – 14.4
Squares and Square Roots : Exercise – 6.3	Introduction to Graphs : Exercise – 15.1
Squares and Square Roots : Exercise – 6.4	Introduction to Graphs : Exercise – 15.2
Cubes and Cube Roots : Exercise – 7.1	Introduction to Graphs : Exercise – 15.3
Cubes and Cube Roots : Exercise – 7.2	Playing with Numbers : Exercise – 16.1
	Playing with Numbers : Exercise – 16.2

Class 8 Mathematics MCQ Direct And Inverse Proportions

NCERT Class 8 Mathematics MCQ
Direct And Inverse Proportions with Answers

CBSE Class 8 Mathematics MCQ Exponents and Powers with Answers

CBSE Class 8 Mathematics MCQ Mensuration with Answers

MCQ Questions Mechanical Engineering Hydraulic Machines

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Class 8 Mathematics MCQ Direct And Inverse Proportions

NCERT Class 8 Mathematics MCQ Direct And Inverse Proportions with Answers

CBSE Class 8 Mathematics MCQ Exponents and Powers with Answers

CBSE Class 8 Mathematics MCQ Mensuration with Answers

MCQ Questions Mechanical Engineering Hydraulic Machines

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NCERT Class 8 Mathematics MCQ
Direct And Inverse Proportions with Answers