Simple Interest Questions with Answers (Class 6–8)

Simple interest is the extra money you earn or pay when you lend or borrow money. It is calculated only on the original amount (called the principal) and stays the same each year unlike compound interest.

For example, if you lend Rs. 1,000 at 5% per year, you earn Rs. 50 every year. The interest does not increase over time.

These simple interest questions are suitable for Class 6, 7, and 8 students.

Table of Contents

• Simple Interest Formula
• Solved Examples of Simple Interest
• Practice Questions on Simple Interest
• Conclusion
• Frequently Asked Questions on Simple Interest

Simple Interest Formula

The formula for simple interest in mathematics is:

Simple Interest (SI) = (P × R × T) / 100

Where:

• P = Principal (original amount of money)

• R = Rate of interest per annum (in %)

• T = Time (in years)

Learn more on simple interest

How to Solve Simple Interest Questions (Steps)

Step 1: Identify the given values - Principal (P), Rate (R), and Time (T) from the question.

Step 2: Write the Simple Interest formula - SI = (P × R × T) / 100

Step 3: Put the values of P, R, and T in their respective places.

Step 4: Multiply P × R × T, then divide by 100.

Step 5: Write the final answer with proper unit (Rs.)

Example

Question: Find the simple interest on Rs. 1,000 at 5% per annum for 2 years.

Solution:
Step 1: Write the formula
SI = (P × R × T) / 100

Step 2: Substitute the values
SI = (1000 × 5 × 2) / 100

Step 3: Simplify
SI = 10000 / 100

Step 4: Final Answer
SI = Rs. 100

Answer: The simple interest is Rs. 100.

Read more:

• Compound Interest Questions
• Compound Interest
• Profit and Loss Questions
• Percentage Questions

Solved Examples of Simple Interest Questions

Solved Examples - Easy Level

Question 1: Find the simple interest on Rs. 1,000 at 5% per annum for 2 years.
Solution:
SI = (P × R × T) / 100
SI = (1000 × 5 × 2) / 100 = Rs. 100

Question 2: Calculate the simple interest on Rs. 2,500 at 4% per annum for 3 years.
Solution:
SI = (P × R × T) / 100
SI = (2500 × 4 × 3) / 100 = Rs. 300

Question 3: A sum of Rs. 800 is invested at 10% per annum for 1 year. Find the interest.
Solution:
SI = (P × R × T) / 100
SI = (800 × 10 × 1) / 100 = Rs. 80

Question 4: Find the interest on Rs. 1,200 at 6% per annum for 2 years.
Solution:
SI = (P × R × T) / 100
SI = (1200 × 6 × 2) / 100 = Rs. 144

Question 5: What is the simple interest on Rs. 3,000 at 5% per annum for 1 year?
Solution:
SI = (P × R × T) / 100
SI = (3000 × 5 × 1) / 100 = Rs. 150

Solved Examples - Medium Level

Question 1: Find the total amount on Rs. 5,000 at 8% per annum for 2 years.
Solution:
SI = (5000 × 8 × 2) / 100 = Rs. 800
Amount = 5000 + 800 = Rs. 5,800

Question 2: A sum earns Rs. 600 as simple interest in 3 years at 5% per annum. Find the principal.
Solution:
SI = (P × R × T) / 100
P = (SI × 100) / (R × T)
P = (600 × 100) / (5 × 3) = Rs. 4,000

Question 3: At what rate will Rs. 2,000 earn Rs. 400 in 4 years?
Solution:
SI = (P × R × T) / 100
R = (SI × 100) / (P × T)
R = (400 × 100) / (2000 × 4) = 5%

Question 4: How long will it take for Rs. 1,500 to earn Rs. 450 at 6% per annum?
Solution:
SI = (P × R × T) / 100
T = (SI × 100) / (P × R)
T = (450 × 100) / (1500 × 6) = 5 years

Question 5: Find the simple interest on Rs. 4,000 at 7.5% per annum for 3 years.
Solution:
SI = (P × R × T) / 100
SI = (4000 × 7.5 × 3) / 100 = Rs. 900

Solved Examples - Advanced Level

Question 1: A sum becomes Rs. 6,600 in 2 years at 10% per annum. Find the principal.
Solution:
Amount = P + SI
SI = (P × 10 × 2) / 100 = 0.2P
So, Amount = P + 0.2P = 1.2P
1.2P = 6600 ⇒ P = Rs. 5,500

Question 2: Find the rate if Rs. 3,000 amounts to Rs. 3,900 in 5 years.
Solution:
SI = 3900 − 3000 = Rs. 900
R = (900 × 100) / (3000 × 5) = 6%

Question 3: A person invests Rs. 2,500 for 3 years and gets Rs. 600 as interest. Find the rate.
Solution:
SI = (P × R × T) / 100
R = (600 × 100) / (2500 × 3) = 8%

Question 4: In how many years will Rs. 2,000 become Rs. 3,200 at 10% per annum?
Solution:
SI = 3200 − 2000 = Rs. 1200
T = (1200 × 100) / (2000 × 10) = 6 years

Question 5: The difference between the amounts of Rs. 5,000 for 2 years and 4 years is Rs. 600. Find the rate.
Solution:
Extra time = 2 years
Interest for 2 years = Rs. 600
SI = (P × R × T) / 100
600 = (5000 × R × 2) / 100
600 = 100R
R = 6%

Practice Questions on Simple Interest

1. Find the simple interest on Rs. 2,500 at 4% per annum for 3 years.
2. A sum of Rs. 6,000 is invested at 5% per annum for 2 years. Calculate the interest earned.
3. How much interest will Rs. 1,200 earn in 5 years at 3% per annum?
4. If the simple interest on Rs. 4,000 for 2 years is Rs. 320, find the rate of interest.
5. How long will it take for Rs. 3,000 to earn Rs. 450 at 5% per annum?
6. A sum amounts to Rs. 5,600 in 4 years at 5% simple interest. Find the principal.
7. What rate of interest will turn Rs. 2,000 into Rs. 2,400 in 5 years under simple interest?
8. Find the total amount when Rs. 3,500 is invested at 6% per annum for 3 years.
9. A person earns Rs. 900 as interest on a sum in 3 years at 6% per annum. Find the principal.
10. In how many years will Rs. 1,500 amount to Rs. 1,950 at 10% simple interest?

Conclusion

Simple interest is easy to learn and useful in real life. Once you know the formula, you can quickly work out how much interest is earned or paid on any amount.

Frequently Asked Questions on Simple Interest Questions

1. What is simple interest?

Answer: Simple interest is the extra amount earned or paid on money over time, calculated only on the original amount (principal).

2. What is the formula for simple interest?

Answer: The formula is: Simple Interest (SI) = (P × R × T) / 100,
where P = principal, R = rate of interest per year, and T = time in years.

3. What is the difference between simple interest and compound interest?

Answer: Simple interest is calculated only on the principal, while compound interest is calculated on the principal plus previously earned interest.

4. Where is simple interest used in real life?

Answer: Simple interest is used in bank savings, loans, business transactions, EMI plans, and personal lending.

5. Is simple interest easy to learn for students?

Answer: Yes, simple interest is one of the easiest financial concepts and is commonly taught in school mathematics.

 

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