Class 8 RS Aggarwal Maths Compound Interest Solutions - Free PDF Download
FAQs on RS Aggarwal Class 8 Mathematics Solutions for Chapter-11 Compound Interest
1. What are the main formulas for Compound Interest used in RS Aggarwal Class 8 Chapter 11?
The primary formulas you will use when solving problems in RS Aggarwal Chapter 11 are:
- Amount (A): To find the total amount after interest, the formula is A = P(1 + R/100)ⁿ, where 'P' is the Principal, 'R' is the Rate of Interest per annum, and 'n' is the time in years.
- Compound Interest (CI): To find only the interest earned, you calculate the Amount first and then subtract the Principal: CI = A - P, which is the same as CI = P[(1 + R/100)ⁿ - 1].
2. How many exercises are in RS Aggarwal's Class 8 Maths Chapter 11, and what do they cover?
Chapter 11, Compound Interest, in the RS Aggarwal textbook for Class 8 contains four main exercises (11A, 11B, 11C, and 11D). These are structured to build your skills progressively:
- Exercise 11A: Focuses on the basic calculation of amount and compound interest compounded annually.
- Exercise 11B: Introduces problems where interest is compounded half-yearly or quarterly.
- Exercise 11C: Covers practical, application-based problems like population growth and asset depreciation.
- Exercise 11D: Deals with more complex scenarios, such as finding the principal, rate, or time when other values are given.
3. Are the solutions for RS Aggarwal Class 8 Maths Chapter 11 helpful for CBSE exam preparation?
Yes, using the step-by-step solutions for RS Aggarwal Chapter 11 is highly beneficial for exam preparation. While NCERT builds the foundation, RS Aggarwal provides a wide variety of questions that strengthen your problem-solving skills. The detailed solutions help you understand the correct methodology to apply for different types of problems, which is crucial for scoring well in CBSE exams as per the 2025-26 syllabus.
4. How is the calculation of compound interest different when it is compounded half-yearly versus annually?
The key difference lies in how the rate and time are adjusted. When interest is compounded annually, you use the given annual rate (R) and time in years (n). However, for half-yearly compounding:
- The rate of interest is halved (R/2), as interest is calculated for a 6-month period.
- The time period is doubled (2n), as there are two compounding periods in each year.
This distinction is critical for solving problems accurately in exercises like 11B.
5. Why is it important to solve RS Aggarwal questions for Chapter 11 after completing the NCERT textbook?
The NCERT textbook is excellent for understanding the fundamental concepts of Compound Interest. However, RS Aggarwal serves as the next logical step for practice and mastery. It offers a greater volume and variety of problems, including many Higher Order Thinking Skills (HOTS) questions. This extensive practice ensures that you can handle any variation of a question in your exams, improving both your speed and accuracy.
6. What types of application-based problems are found in RS Aggarwal Chapter 11 on Compound Interest?
RS Aggarwal Chapter 11 includes several real-world applications of the compound interest formula, which are important for exams. These typically involve:
- Calculating the growth of population over a few years at a fixed annual rate.
- Determining the depreciated value of an asset, like a car or machine, whose value decreases over time.
- Finding the growth in the number of bacteria or the value of an investment.
7. What is a common mistake students make when solving CI problems from RS Aggarwal Chapter 11?
One of the most frequent errors is correctly calculating the final Amount (A) but forgetting the final step: subtracting the Principal (P) to find the Compound Interest (CI). Another common pitfall is misapplying the rules for half-yearly compounding, either by forgetting to halve the rate or double the time period. Careful, step-by-step work is key to avoiding these mistakes.
8. Can the formula A = P(1 + R/100)ⁿ be used to find the Principal (P) in RS Aggarwal questions?
Yes, absolutely. A significant type of question in RS Aggarwal's Chapter 11 involves algebraic manipulation of the core formula. You will often be given the final Amount (A), the rate (R), and the time (n), and your task will be to rearrange the formula to solve for the initial Principal (P). This tests your understanding beyond simple substitution.











