# Class 8 Maths Chapter 13 Direct and Inverse Proportions MCQs

**Class 8 Maths Chapter 13 – Direct and Inverse Proportions MCQs Questions** are available online for students, with solved answers. These objective questions are designed by our subject experts, according to **CBSE syllabus (2021-2022)** and **NCERT** guidelines. The chapter-wise multiple-choice questions are given at BYJU’S to make every student learn each chapter thoroughly and support them to score better. Also, learn important questions for class 8 Maths here.

Practice more and test your skills on Class 8 Maths Chapter 13 Direct and Inverse Proportions MCQs with the given PDF here.

## MCQs Questions on Class 8 Direct and Inverse Proportions with Answers

Multiple choice questions (MCQs) are given for Class 8 Direct and Inverse Proportions chapter. Students need to solve each question here and select the appropriate option.

**1. 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

Answer: **A**

Explanation: x = 20 and y = 40

Clearly, 40 = 2 x 20

y=2x

y∝x, where 2 is the proportionality constant.

**2. 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

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.

**3. If x and y are directly proportional, then which of the following is correct?**

A. x+y=constant

B. x-y=constant

C. xy=constant

D. x/y=constant

Answer:** D**

Explanation: x∝y

x=ky

k=x/y, where k is a constant.

**4. If x and y are inversely proportional, then:**

A. x+y=constant

B. x-y=constant

C. xy=constant

D. x/y=constant

Answer: **C**

Explanation: x∝1/y

x=k/y

xy=k

Where k is a constant.

**5. If x∝y and x _{1}=5,y_{1}=210 and x_{2} = 2, then find y_{2}?**

A. 200

B. 84

C. 99

D. 70

Answer: **B**

Explanation: x∝y

x=ky

x/y=k

x_{1}/y_{1} = x_{2}/y_{2}

5/210 = 2/y_{2}

y_{2} = 84

**6. 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

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

**7. 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

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.

**8. If x and y are inversely proportional, then which one is true?**

A. x_{1}/y_{1} = x_{2}/y_{2}

B. x_{1}/x_{2} = y_{1}/y_{2}

C. x_{1}/x_{2} = y_{2}/y_{1}

D. x_{1}.x_{2} = y_{1}.y_{2}

Answer: **C**

Explanation: x∝1/y

x=k(1/y)

xy=k

x_{1}y_{1}=x_{2}y_{2}

x_{1}/x_{2}=y_{2}/y_{1}

**9. 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

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

**10. 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

Answer: **D**

Explanation: 12 × 50 = x × 40

x = (12×50)/40 = 15

**11. 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

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

**12. If 300 Kg of coal cost 6000₹, then find the cost of 120 kg of coal?**

A. 1200₹

B. 2400₹

C. 3200₹

D. 4200₹

Answer: B

Solution:

300/6000 = 120/x

x = 2400

**13. Manvi types 200 words in 30 minutes. How many words she will type in 12 minutes?**

A. 100

B. 80

C. 60

D. 50

Answer: B

Solution:

30/200 = 12/x

x = 12 x 200/30

x = 80

**14. 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

Answer: B. 60 days

40 × 120 = 80 × x

⇒ x = 60

**15. 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

Answer: A. 96 minutes

80 × 6 = x × 5

x = 96

**16. **** 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

Answer: D. 15

12 × 50 = x × 40

x = (12 × 50)/40 = 15

**17. 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

Answer: C. 16

100 × 20 = 125 × x

x = 16

**18. 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

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.

**19. 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

Answer: C. 9 hours

720/18 = 360/x

**20. 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

Answer: A. Direct Proportion