Solved NCERT Questions For Class 8 Maths Chapter 13 In Hindi - Free PDF
FAQs on NCERT Solutions For Class 8 Maths Chapter 13 Direct And Inverse Proportions in Hindi - 2025-26
1. Where can I find accurate and step-by-step NCERT Solutions for Class 8 Maths Chapter 13 for the 2025-26 session?
You can find comprehensive and expert-verified NCERT Solutions for Class 8 Maths Chapter 13, Direct and Inverse Proportions, on Vedantu. Our solutions are crafted by subject matter experts to provide a clear, step-by-step methodology for every problem, strictly following the CBSE 2025-26 guidelines. They are available online and can also be downloaded for offline use.
2. What are the main topics for which solutions are provided in NCERT Class 8 Maths Chapter 13?
The NCERT Solutions for Class 8 Maths Chapter 13 primarily cover two fundamental concepts:
- Direct Proportion: Solutions for problems where two quantities increase or decrease together at a constant rate (e.g., more items purchased result in a higher cost).
- Inverse Proportion: Solutions for problems where an increase in one quantity causes a proportional decrease in another, and vice-versa (e.g., more workers completing a job in less time).
3. How many exercises are there in Chapter 13 of the Class 8 Maths NCERT textbook, and what do they focus on?
The NCERT Class 8 Maths Chapter 13, 'Direct and Inverse Proportions', contains two exercises. The solutions for these are structured as follows:
- Exercise 13.1: Focuses on problems related to Direct Proportion.
- Exercise 13.2: Focuses on problems related to Inverse Proportion.
4. What is the correct method to identify if a word problem requires a direct or inverse proportion solution?
As demonstrated in the NCERT solutions, the correct method involves a logical check:
- First, identify the two main quantities in the problem (e.g., number of workers and days taken).
- Then, ask yourself: 'If I increase the first quantity, what happens to the second?'
- If the second quantity also increases, it is a case of direct proportion (use x/y = k).
- If the second quantity decreases, it is a case of inverse proportion (use x * y = k).
This analytical step is crucial before applying any formula and is clearly explained in every solved example.
5. What is a common mistake made in solving inverse proportion problems, and how do the NCERT solutions help prevent it?
A very common mistake is applying the formula for direct proportion (x₁/y₁ = x₂/y₂) to an inverse proportion problem. The NCERT solutions prevent this by emphasizing that in inverse proportion, the product of the quantities remains constant, not their ratio. The correct relationship to use is x₁y₁ = x₂y₂. Our solutions clearly show the setup for both types, helping students avoid this conceptual error.
6. How do the NCERT Solutions for Chapter 13 explain the role of the 'constant of proportionality' (k)?
The NCERT Solutions explain the 'constant of proportionality' (k) as the fixed value that defines the relationship between two quantities.
- In direct proportion, it's the constant ratio (k = x/y). The solutions show how to calculate 'k' from one given pair of values and use it to find any unknown value.
- In inverse proportion, it's the constant product (k = x × y). The solutions demonstrate how this constant product is the key to solving for missing terms in the relationship.
7. Why is it incorrect to use the same formula for both direct and inverse proportion problems? What is the core difference in the approach?
It is incorrect because the fundamental relationship between the quantities is different. The core difference explained in the NCERT solutions is:
- Direct Proportion: The quantities move in the same direction (both increase or both decrease). Their ratio is constant. For example, if you double the speed, you cover double the distance in the same time.
- Inverse Proportion: The quantities move in opposite directions (one increases, the other decreases). Their product is constant. For example, if you double your speed, you take half the time to cover the same distance.
Using the wrong formula leads to a completely wrong answer because it misrepresents this core relationship.
8. How do the NCERT Solutions for Class 8 Maths apply proportion concepts to real-world scenarios like speed, distance, and time?
The solutions break down real-world problems into mathematical relationships. For instance:
- Speed and Time (Inverse Proportion): To cover a fixed distance, if speed increases, the time taken decreases. The solutions will guide you to set up the problem using the x₁y₁ = x₂y₂ formula (Speed₁ × Time₁ = Speed₂ × Time₂).
- Distance and Time (Direct Proportion): At a constant speed, if you travel for more time, you cover more distance. The solutions demonstrate how to use the x₁/y₁ = x₂/y₂ formula for this scenario (Distance₁/Time₁ = Distance₂/Time₂).
9. What is the correct step-by-step approach to solving a typical question from Exercise 13.2 (Inverse Proportion)?
To solve a problem from Exercise 13.2, the NCERT solutions guide you through the following steps:
- Read the problem and create a table with the two quantities (e.g., 'Number of Pipes' and 'Time to Fill Tank').
- Identify the known pair of values (x₁, y₁) and the pair with an unknown value (x₂, y₂).
- Confirm it is inverse proportion (e.g., more pipes will take less time).
- Set up the equation based on the principle that the product is constant: x₁ × y₁ = x₂ × y₂.
- Substitute the known values into the equation and solve for the unknown variable.






















