CAT Simple and Compound Interest Questions 2026: Practice Questions with Answers & PDF

Overview: If you are preparing for CAT Quantitative Aptitude, CAT Simple and Compound Interest Questions are one of the most scoring areas in Arithmetic. These questions are usually based on interest, amount, principal, time, population growth, depreciation, installments and percentage change.

CAT Exam may not always ask direct formula-based questions, but the concepts of Simple Interest and Compound Interest are often tested through application-based problems. In this blog, you will learn formulas, tricks, examples and practice questions to strengthen this topic.

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What You Will Learn in This Blog

• Meaning of Simple Interest and Compound Interest
• Important formulas for CAT
• Difference between SI and CI
• Population, depreciation and installment-based questions
• Practice questions with answers
• Tips to solve interest questions faster

Key Takeaways

• Simple and Compound Interest Questions for CAT are part of Arithmetic.
• Most CAT questions are application-based, not direct formula-based.
• Population growth and depreciation follow the compound interest concept.
• Installment-based questions are important for advanced practice.
• Regular practice improves speed and accuracy.

Table of Contents

1. What are CAT Simple and Compound Interest Questions?
2. Why are Simple and Compound Interest Important for CAT?
3. Difference Between Simple Interest and Compound Interest
4. Important Terminologies Pertaining to Interest
5. Important Formulas for CAT Compound Interest Questions PDF
6. Compound Interest Installment Questions
7. Population Growth and Depreciation Questions
8. CAT Simple and Compound Interest Questions with Answers
9. Tips to Solve Simple and Compound Interest Questions for CAT
10. Common Mistakes to Avoid
11. CAT Compound Interest Questions PDF
12. Conclusion

What are CAT Simple and Compound Interest Questions?

CAT Simple and Compound Interest Questions test your understanding of money, time and rate of interest. The basic idea is simple: the value of money changes with time. A rupee today is not equal to a rupee tomorrow.

When money is borrowed or invested, an extra amount is paid or received over time. This extra amount is called interest. CAT exam pattern uses this concept in questions related to loans, bank deposits, investments, depreciation and population change.

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Why are Simple and Compound Interest Important for CAT?

Simple and Compound Interest Questions for CAT are important because they are closely connected with Percentages, Profit and Loss, Ratio, Growth and Decay. A strong hold on this topic can help you solve many Arithmetic-based questions faster.

Area	CAT Relevance
Simple Interest	Basic arithmetic and direct calculation
Compound Interest	Growth-based and application questions
Installments	Loan and repayment-based questions
Population Growth	Compound growth application
Depreciation	Compound decrease application

Difference Between Simple Interest and Compound Interest

Before solving CAT Simple and Compound Interest Questions, it is important to understand the basic difference between SI and CI.

Simple Interest	Compound Interest
Calculated only on the principal amount	Calculated on principal plus previous interest
Interest remains the same every year	Interest increases every year
Formula is easier	Formula involves powers
Used for basic loan questions	Used for growth, decay and investment questions

Important Terminologies Pertaining to Interest

• Creditor: The person who lends money.
• Debtor: The person who borrows money.
• Principal: The amount of money initially borrowed or invested.
• Time: The period for which money is borrowed or invested.
• Interest: The extra money paid or received on the principal.
• Amount: The sum of principal and total interest.

Amount = Principal + Total Interest

Important Formulas for CAT Simple and Compound Interest Questions

Simple Interest Formula

SI = (P × R × T) / 100

Here, P is Principal, R is Rate of Interest and T is Time.

Amount in Simple Interest

Amount = Principal + Simple Interest

Compound Interest When Compounded Annually

Amount = P(1 + R/100)ⁿ

Compound Interest When Compounded Half-Yearly

Amount = P(1 + R/200)²ⁿ

Compound Interest When Compounded Quarterly

Amount = P(1 + R/400)⁴ⁿ

When Rates are Different for Different Years

Amount = P(1 + R1/100)(1 + R2/100)(1 + R3/100)

Present Worth Formula

Present Worth = Future Value / (1 + R/100)ⁿ

When a Sum Becomes x Times in n Years

R = 100[(x)^1/n - 1]

Finding Rate from Two Successive Amounts

R = [(A2 - A1) / A1] × 100

Compound Interest Installment Questions

Installment questions are based on loans. If a person borrows money from a bank and agrees to repay it in equal yearly installments, the present value of all installments must be equal to the loan amount.

These questions are important for advanced CAT Arithmetic questions for practice because they combine Compound Interest, Present Value and logical calculation.

Example

A person takes a loan of ₹10,000 at 10% compound interest and repays it in 2 equal yearly installments. Find the installment.

Solution:

Let each installment be X.

10000 = X/(1.1) + X/(1.1)²

By solving this equation, we can find the value of X.

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Population Growth and Depreciation Questions

Population growth questions follow the same formula as Compound Interest. The only difference is that the rate of population growth replaces the rate of interest.

If population increases:

Final Population = Initial Population × (1 + R/100)ⁿ

If population decreases or value depreciates:

Final Value = Initial Value × (1 - R/100)ⁿ

CAT Simple and Compound Interest Questions with Answers

Easy Level Questions

Q1. Find the simple interest on ₹5000 at 10% per annum for 2 years.

A. ₹500
B. ₹800
C. ₹1000
D. ₹1200

Answer: C. ₹1000

Q2. A sum of ₹8000 is invested at 5% simple interest for 3 years. Find the interest.

A. ₹1000
B. ₹1200
C. ₹1400
D. ₹1600

Answer: B. ₹1200

Q3. A sum becomes ₹6000 in 2 years at 10% simple interest. Find the principal.

A. ₹4000
B. ₹4500
C. ₹5000
D. ₹5500

Answer: C. ₹5000

Q4. Find the compound amount on ₹10000 at 10% per annum for 2 years.

A. ₹11000
B. ₹12000
C. ₹12100
D. ₹12500

Answer: C. ₹12100

Q5. The compound interest on ₹5000 at 10% per annum for 2 years is:

A. ₹1000
B. ₹1050
C. ₹1100
D. ₹1150

Answer: B. ₹1050

Moderate Level Questions

Q6. A sum doubles itself in 5 years at simple interest. In how many years will it become 4 times?

A. 10 years
B. 12 years
C. 15 years
D. 20 years

Answer: C. 15 years

Q7. A sum becomes ₹12100 in 2 years at 10% compound interest. Find the principal.

A. ₹9000
B. ₹9500
C. ₹10000
D. ₹10500

Answer: C. ₹10000

Q8. A machine depreciates by 10% every year. If its present value is ₹50000, what will be its value after 2 years?

A. ₹40000
B. ₹40500
C. ₹41000
D. ₹42000

Answer: B. ₹40500

Q9. The population of a town increases by 20% every year. If the current population is 10000, what will be the population after 2 years?

A. 12000
B. 13000
C. 14000
D. 14400

Answer: D. 14400

Q10. At compound interest, a sum becomes ₹11000 after 1 year and ₹12100 after 2 years. Find the rate of interest.

A. 8%
B. 9%
C. 10%
D. 12%

Answer: C. 10%

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Q11. A sum of ₹8,000 is invested at 10% compound interest per annum. What will be the amount after 3 years?

A. ₹10,120
B. ₹10,648
C. ₹10,920
D. ₹11,000

Answer: B. ₹10,648

Q12. At what rate of simple interest will ₹5,000 become ₹6,500 in 3 years?

A. 8%
B. 9%
C. 10%
D. 12%

Answer: C. 10%

Q13. The compound interest on ₹20,000 for 2 years at 5% per annum is:

A. ₹2,000
B. ₹2,025
C. ₹2,050
D. ₹2,100

Answer: C. ₹2,050

Q14. A sum amounts to ₹24,200 after 2 years at 10% compound interest. Find the principal.

A. ₹18,000
B. ₹19,000
C. ₹20,000
D. ₹22,000

Answer: C. ₹20,000

Q15. What is the simple interest on ₹12,000 at 15% per annum for 4 years?

A. ₹6,000
B. ₹6,800
C. ₹7,000
D. ₹7,200

Answer: D. ₹7,200

Q16. A machine depreciates by 20% every year. Its present value is ₹50,000. What will be its value after 2 years?

A. ₹30,000
B. ₹31,000
C. ₹32,000
D. ₹33,000

Answer: C. ₹32,000

Q17. A population increases by 5% every year. If the current population is 40,000, what will it be after 2 years?

A. 43,500
B. 44,000
C. 44,100
D. 45,000

Answer: C. 44,100

Q18. Find the compound interest on ₹16,000 at 25% per annum for 2 years.

A. ₹8,500
B. ₹9,000
C. ₹9,500
D. ₹10,000

Answer: B. ₹9,000

Q19. A sum becomes ₹8,820 in 2 years at 5% compound interest. Find the principal.

A. ₹7,800
B. ₹8,000
C. ₹8,200
D. ₹8,500

Answer: B. ₹8,000

Q20. The difference between Compound Interest and Simple Interest on ₹10,000 for 2 years at 10% is:

A. ₹50
B. ₹100
C. ₹150
D. ₹200

Answer: B. ₹100

Q21. A sum doubles itself in 8 years at compound interest. In how many years will it become four times?

A. 12 years
B. 14 years
C. 16 years
D. 18 years

Answer: C. 16 years

Q22. What principal will amount to ₹13,310 in 3 years at 10% compound interest?

A. ₹9,000
B. ₹10,000
C. ₹11,000
D. ₹12,000

Answer: B. ₹10,000

Q23. Find the simple interest on ₹7,500 at 12% for 5 years.

A. ₹4,000
B. ₹4,200
C. ₹4,500
D. ₹4,800

Answer: C. ₹4,500

Q24. A sum becomes ₹15,625 in 4 years at 25% compound interest. Find the principal.

A. ₹6,000
B. ₹6,400
C. ₹6,800
D. ₹7,000

Answer: B. ₹6,400

Q25. If ₹15,000 earns ₹3,600 as simple interest in 3 years, what is the annual rate?

A. 6%
B. 7%
C. 8%
D. 9%

Answer: C. 8%

Q26. At compound interest, ₹12,000 becomes ₹13,230 in one year. Find the rate of interest.

A. 8%
B. 9%
C. 10%
D. 10.25%

Answer: D. 10.25%

Q27. A laptop loses 15% of its value every year. If its current price is ₹80,000, what will be its value after one year?

A. ₹66,000
B. ₹67,000
C. ₹68,000
D. ₹68,500

Answer: C. ₹68,000

Q28. A sum invested at simple interest becomes ₹18,000 after 4 years. The principal was ₹15,000. Find the rate.

A. 4%
B. 5%
C. 6%
D. 7%

Answer: B. 5%

Q29. Find the amount if ₹25,000 is invested for 2 years at 8% compound interest.

A. ₹28,800
B. ₹29,000
C. ₹29,160
D. ₹29,500

Answer: C. ₹29,160

Q30. A bank compounds interest half-yearly at 12% per annum. The amount on ₹10,000 after one year will be:

A. ₹11,200
B. ₹11,236
C. ₹11,250
D. ₹11,300

Answer: B. ₹11,236

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Tips to Solve Simple and Compound Interest Questions for CAT

• Revise percentages first: Most interest questions are directly linked with percentage change.
• Memorize common powers: Values like 1.1², 1.2² and 1.05² save time.
• Understand the question type: Check whether the question is based on SI, CI, population or depreciation.
• Avoid unnecessary expansion: Use shortcuts and approximation wherever possible.
• Practice installment questions: These are slightly tricky but highly useful for CAT-level preparation.

Common Mistakes to Avoid

• Using the Simple Interest formula in Compound Interest questions.
• Forgetting to adjust rate and time in half-yearly or quarterly compounding.
• Confusing growth with depreciation.
• Ignoring the word “annually”, “half-yearly” or “quarterly”.
• Not reading whether the question asks for Interest or Amount.

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CAT Compound Interest Questions PDF

A CAT compound interest questions PDF can help you revise formulas and practice questions in one place. The PDF should ideally include formula sheets, solved examples, CAT-level questions, shortcut notes and previous year-based practice questions.

Practicing  from a CAT compound interest questions PDF regularly can improve your calculation speed and help you revise before mocks.

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Conclusion

In CAT syllabus the Simple and Compound Interest Questions are important for building a strong base in Arithmetic. These questions may look formula-based, but CAT often tests them through practical situations like population growth, depreciation, installments and investments.

To master this topic, understand the concepts, revise formulas, solve different question types and practice regularly from mocks and a CAT compound interest questions PDF. With the right approach, Simple and Compound Interest Questions for CAT can become one of your most scoring areas in Quant.