Class 7 RS Aggarwal Chapter-12 Simple Interest Solutions - Free PDF Download
FAQs on RS Aggarwal Class 7 Solutions Chapter-12 Simple Interest
1. What are the key formulas needed to solve the problems in RS Aggarwal Class 7 Maths Chapter 12, Simple Interest?
To solve the problems in this chapter, you must be familiar with three core formulas:
To calculate Simple Interest (SI): SI = (Principal × Rate × Time) / 100. This is the primary formula used in most questions.
To calculate the total Amount (A): Amount = Principal + Simple Interest. This is used to find the total sum to be paid back.
To find Principal, Rate, or Time: The main formula can be rearranged to find other values. For example, to find the Principal (P), you would use P = (100 × SI) / (Rate × Time).
2. How are the exercises structured in RS Aggarwal Class 7 Chapter 12 solutions for Simple Interest?
Chapter 12 on Simple Interest is divided into two main exercises, 12A and 12B. The solutions are structured to follow this progression:
Exercise 12A: These questions focus on the direct application of the simple interest formula. You will be asked to calculate the simple interest and the total amount when the principal, rate, and time are provided.
Exercise 12B: This exercise presents more complex problems. Here, you might be given the simple interest and be required to work backward to find the Principal, Rate, or Time.
3. What is the correct step-by-step method to find the total Amount in a typical RS Aggarwal Exercise 12A problem?
To find the total amount payable, follow these precise steps as per the methodology in RS Aggarwal solutions:
Identify the Given Values: First, clearly write down the Principal (P), Rate of Interest (R) per annum, and Time (T) in years from the question.
Calculate the Simple Interest (SI): Use the formula SI = (P × R × T) / 100. Substitute the values and compute the interest earned or due.
Calculate the Total Amount (A): Finally, add the calculated Simple Interest to the original Principal. The formula is Amount = Principal + SI. This final sum is your answer.
4. How do you solve a problem from Chapter 12 when the time is given in months or days, not years?
This is a common variation where you must ensure the units for Rate and Time are consistent. Since the interest rate is almost always given 'per annum' (per year), you must convert the time into years before using the formula.
If Time is in Months: Convert it to years by dividing by 12. For example, 6 months becomes 6/12 = 0.5 years.
If Time is in Days: Convert it to years by dividing by 365. For example, 73 days becomes 73/365 = 1/5 years.
Failing to make this conversion is a frequent source of errors.
5. How do you find the Principal, Rate, or Time if the Simple Interest is already provided in the question?
This type of problem, often found in Exercise 12B, requires you to rearrange the basic SI formula to solve for the unknown variable. The rearranged formulas are:
To find the Principal (P): P = (100 × SI) / (R × T)
To find the Rate (R): R = (100 × SI) / (P × T)
To find the Time (T): T = (100 × SI) / (P × R)
Simply substitute the known values into the correct rearranged formula to find the solution.
6. Why is it so important to use the step-by-step method for solving Simple Interest problems in exams?
Using a clear, step-by-step method is crucial for two main reasons:
Clarity and Accuracy: It breaks down a complex problem into smaller, manageable parts, significantly reducing the chances of calculation errors. By first calculating the Simple Interest and then the Amount, you ensure each component is correct.
Marks Allocation: In school exams, marks are often awarded for each correct step. Showing your work—such as writing the formula, substituting values correctly, and calculating the final answer—can help you get partial credit even if the final answer is wrong.
7. In what real-world situations is the concept of Simple Interest from Chapter 12 applied?
Understanding the solutions for this chapter helps in real life, as simple interest is commonly used for:
Short-Term Loans: Many personal loans or short-term credit from financial institutions use simple interest.
Car Loans: The interest on vehicle financing is often calculated on a simple interest basis over the loan's term.
Basic Savings: Some basic savings accounts or fixed deposits might calculate returns using a simple interest method, especially for fixed, short durations.
