Compound Interest - Complete Guide with 300+ Questions | Competitive Exams

📚 Compound Interest - Complete Guide with 300+ Questions

💡 Exam Preparation: Practice 50+ questions daily for best results in SSC, Banking, Railway, PCS exams!

📖 Type 1: Basic CI Calculation (Questions - 1 to 50)

📝 Question Set 1: Simple Annual Compounding

Q1. Principal = ₹5,000, Rate = 10% p.a., Time = 2 years. Find CI.
Q2. P = ₹8,000, R = 12% p.a., T = 3 years. Calculate CI.
Q3. Principal = ₹2,000, Rate = 5% p.a., Time = 2 years. Find amount and CI.
Q4. P = ₹15,000, R = 8% p.a., T = 2 years. What is CI?
Q5. Principal = ₹10,000, Rate = 20% p.a., Time = 2 years. Find CI.

ANS-1: Amount = 5000 × (110/100)² = ₹6,050, CI = ₹1,050

ANS-2: Amount = 8000 × (112/100)³ = ₹11,736.64, CI = ₹3,736.64

📝 Question Set 2: Higher Rates Practice

Q6. P = ₹50,000, R = 20% p.a., T = 3 years. Find CI.
Q7. Principal = ₹30,000, Rate = 25% p.a., Time = 2 years. Calculate CI.
Q8. P = ₹75,000, R = 15% p.a., T = 3 years. Find amount.
Q9. Principal = ₹1,00,000, Rate = 18% p.a., T = 2 years. Calculate CI.
Q10. P = ₹45,000, R = 30% p.a., T = 2 years. Find CI.

📝 Question Set 3: Mixed Difficulty

Q11. If P = ₹3,000, R = 10%, T = 2 years, find CI.
Q12. P = ₹12,000, R = 12% p.a., T = 3 years. Find CI.
Q13. Principal = ₹8,000, Rate = 15%, Time = 2 years. Calculate CI.
Q14. P = ₹25,000, R = 20% p.a., T = 2 years. Find CI.
Q15. Principal = ₹18,000, Rate = 18%, Time = 2 years. Calculate CI.

📝 Question Set 4: Quick Practice

Q16. P = ₹2,000, R = 10%, T = 2 years. Find CI.
Q17. P = ₹4,000, R = 15%, T = 2 years. Calculate CI.
Q18. Principal = ₹6,000, Rate = 20%, Time = 2 years. Find CI.
Q19. P = ₹10,000, R = 25%, T = 2 years. Find CI.
Q20. P = ₹15,000, R = 30%, T = 2 years. Calculate CI.

📝 Question Set 5: Advanced Basic

Q21. P = ₹7,000, R = 18%, T = 3 years. Find CI.
Q22. P = ₹14,000, R = 22%, T = 3 years. Calculate CI.
Q23. Principal = ₹9,000, Rate = 25%, T = 3 years. Find amount.
Q24. P = ₹3,500, R = 30%, T = 3 years. Find CI.
Q25. Principal = ₹20,000, Rate = 12%, T = 3 years. Calculate CI.

🎯 Type 2: Different Rates for Different Years (Questions - 26 to 50)

📝 Question Set 6: Two-Year Different Rates

Q26. P = ₹10,000, Rates = 10% in 1st year, 12% in 2nd year. Find CI.
Q27. P = ₹15,000, Rates = 8% in 1st year, 10% in 2nd year. Calculate CI.
Q28. P = ₹20,000, Rates = 12% in 1st year, 8% in 2nd year. Find amount.
Q29. P = ₹25,000, Rates = 15% in 1st year, 20% in 2nd year. Find CI.
Q30. P = ₹30,000, Rates = 10% in 1st year, 15% in 2nd year. Calculate CI.

📝 Question Set 7: Three-Year Different Rates

Q31. P = ₹10,000, Rates = 10%, 12%, 15% in 3 years. Find CI.
Q32. P = ₹15,000, Rates = 8%, 10%, 12% in 3 years. Calculate CI.
Q33. P = ₹20,000, Rates = 5%, 10%, 15% in 3 years. Find amount.
Q34. P = ₹25,000, Rates = 10%, 20%, 25% in 3 years. Find CI.
Q35. P = ₹30,000, Rates = 6%, 9%, 12% in 3 years. Calculate CI.

📝 Question Set 8: Banking Rates

Q36. FD: P = ₹50,000, Rates = 6%, 7% in 2 years. Find CI.
Q37. RD: P = ₹30,000, Rates = 8%, 9% in 2 years. Calculate CI.
Q38. Investment: P = ₹40,000, Rates = 10%, 12% in 2 years. Find amount.
Q39. Deposit: P = ₹60,000, Rates = 8%, 10% in 2 years. Find CI.
Q40. Savings: P = ₹75,000, Rates = 12%, 15% in 2 years. Calculate CI.

📝 Question Set 9: Mixed Rates

Q41. P = ₹100,000, Rates = 4%, 6%, 8%, 10% in 4 years. Find CI.
Q42. P = ₹80,000, Rates = 3%, 5%, 7%, 11% in 4 years. Calculate CI.
Q43. P = ₹50,000, Rates = 2%, 4%, 6%, 8% in 4 years. Find amount.
Q44. P = ₹75,000, Rates = 5%, 7%, 9%, 12% in 4 years. Find CI.
Q45. P = ₹120,000, Rates = 3%, 5%, 9%, 11% in 4 years. Calculate CI.

📝 Question Set 10: Real Life Problems

Q46. Loan: P = ₹20,000, Rates = 10%, 12% in 2 years. Find CI.
Q47. Business: P = ₹35,000, Rates = 8%, 10% in 2 years. Calculate CI.
Q48. Property: P = ₹50,000, Rates = 15%, 20% in 2 years. Find amount.
Q49. Stock: P = ₹60,000, Rates = 5%, 8% in 2 years. Find CI.
Q50. Portfolio: P = ₹80,000, Rates = 12%, 15% in 2 years. Calculate CI.

📊 Type 3: Finding Time or Rate (Questions - 51 to 100)

📝 Question Set 11: Finding Time

Q51. P = ₹10,000, CI = ₹3,310, R = 10%. Find time.
Q52. P = ₹15,000, Amount = ₹24,186, R = 10%. Find time.
Q53. P = ₹20,000, Amount = ₹32,800, R = 10%. Find time.
Q54. P = ₹25,000, Amount = ₹40,451, R = 10%. Find time.
Q55. P = ₹30,000, Amount = ₹49,839, R = 10%. Find time.

📝 Question Set 12: Finding Rate

Q56. P = ₹10,000, Amount = ₹12,100, T = 2 years. Find R.
Q57. P = ₹15,000, Amount = ₹21,954, T = 3 years. Find R.
Q58. P = ₹20,000, Amount = ₹32,800, T = 3 years. Find R.
Q59. P = ₹25,000, Amount = ₹40,451, T = 3 years. Find R.
Q60. P = ₹30,000, Amount = ₹49,839, T = 3 years. Find R.

📝 Question Set 13: CI and SI Difference

Q61. P = ₹10,000, R = 10%, T = 2 years. Find SI-CI difference.
Q62. P = ₹15,000, R = 12%, T = 3 years. Find SI-CI difference.
Q63. P = ₹20,000, R = 15%, T = 2 years. Calculate difference.
Q64. P = ₹25,000, R = 20%, T = 3 years. Find difference.
Q65. P = ₹30,000, R = 25%, T = 2 years. Calculate difference.

📝 Question Set 14: Population Problems

Q66. Population 2000 = 10,00,000, Growth = 5% p.a. Population in 3 years?
Q67. City population = 20,00,000, Growth = 8% p.a. Population after 2 years?
Q68. Village population = 5,00,000, Growth = 10% p.a. Population after 4 years?
Q69. Country population = 100,00,000, Growth = 6% p.a. Population after 5 years?
Q70. Town population = 1,50,000, Growth = 12% p.a. Population after 4 years?

📝 Question Set 15: Time Period Problems

Q71. P = ₹10,000, Amount = ₹13,310, R = 10%. Find time.
Q72. P = ₹15,000, Amount = ₹19,890, R = 10%. Find time.
Q73. P = ₹20,000, Amount = ₹27,720, R = 10%. Find time.
Q74. P = ₹25,000, Amount = ₹36,720, R = 10%. Find time.
Q75. P = ₹30,000, Amount = ₹47,400, R = 10%. Find time.

🔄 Type 4: Different Compounding Periods (Questions - 101 to 150)

📝 Question Set 16: Half-Yearly Compounding

Q101. P = ₹10,000, R = 10% p.a., T = 2 years. Half-yearly CI.
Q102. P = ₹15,000, R = 12% p.a., T = 3 years. Half-yearly CI.
Q103. P = ₹20,000, R = 15% p.a., T = 2 years. Half-yearly amount.
Q104. P = ₹25,000, R = 20% p.a., T = 3 years. Half-yearly CI.
Q105. P = ₹30,000, R = 18% p.a., T = 2 years. Half-yearly amount.

📝 Question Set 17: Quarterly Compounding

Q106. P = ₹10,000, R = 12% p.a., T = 2 years. Quarterly CI.
Q107. P = ₹15,000, R = 15% p.a., T = 3 years. Quarterly CI.
Q108. P = ₹20,000, R = 18% p.a., T = 2 years. Quarterly amount.
Q109. P = ₹25,000, R = 20% p.a., T = 3 years. Quarterly CI.
Q110. P = ₹30,000, R = 24% p.a., T = 2 years. Quarterly CI.

📝 Question Set 18: Monthly Compounding

Q111. P = ₹10,000, R = 12% p.a., T = 2 years. Monthly CI.
Q112. P = ₹15,000, R = 15% p.a., T = 3 years. Monthly CI.
Q113. P = ₹20,000, R = 18% p.a., T = 2 years. Monthly amount.
Q114. P = ₹25,000, R = 20% p.a., T = 3 years. Monthly CI.
Q115. P = ₹30,000, R = 24% p.a., T = 2 years. Monthly CI.

📝 Question Set 19: Effective Rate Problems

Q116. 12% p.a. compounded half-yearly. Find effective rate.
Q117. 15% p.a. compounded quarterly. Find effective rate.
Q118. 18% p.a. compounded monthly. Find effective rate.
Q119. 20% p.a. compounded half-yearly. Find effective rate.
Q120. 24% p.a. compounded quarterly. Find effective rate.

📝 Question Set 20: Comparison Problems

Q121. Compare annual vs half-yearly: P = ₹10,000, R = 12%, T = 1 year.
Q122. Compare annual vs quarterly: P = ₹15,000, R = 15%, T = 1 year.
Q123. Compare half-yearly vs quarterly: P = ₹20,000, R = 12%, T = 2 years.
Q124. Compare annual vs monthly: P = ₹25,000, R = 15%, T = 2 years.
Q125. Compare all periods: P = ₹30,000, R = 20%, T = 2 years.

🏦 Type 5: Banking and Investment Problems (Questions - 151 to 200)

📝 Question Set 21: FD Problems

Q151. FD: P = ₹50,000, R = 8% p.a., T = 3 years. Maturity amount?
Q152. FD: P = ₹75,000, R = 9% p.a., T = 2 years. Interest earned?
Q153. FD: P = ₹1,00,000, R = 10% p.a., T = 3 years. Maturity amount?
Q154. FD: P = ₹1,25,000, R = 8% p.a., T = 2 years. Interest earned?
Q155. FD: P = ₹1,50,000, R = 10% p.a., T = 3 years. Maturity amount?

📝 Question Set 22: RD Problems

Q156. RD: P = ₹2,000/month, R = 8% p.a., T = 2 years. Total amount?
Q157. RD: P = ₹3,000/month, R = 9% p.a., T = 3 years. Total interest?
Q158. RD: P = ₹4,000/month, R = 10% p.a., T = 2 years. Total amount?
Q159. RD: P = ₹5,000/month, R = 8% p.a., T = 3 years. Total interest?
Q160. RD: P = ₹6,000/month, R = 10% p.a., T = 2 years. Total amount?

📝 Question Set 23: Investment Comparison

Q161. Compare FD vs RD: P = ₹1,00,000 vs ₹8,333/month for 3 years @ 8%.
Q162. Compare two FDs: P1 = ₹1,00,000 @ 8% vs P2 = ₹90,000 @ 9% for 3 years.
Q163. Investment choice: FD with quarterly vs annual compounding.
Q164. Best investment: 12% p.a. quarterly vs 12.36% effective.
Q165. Long term: 10% p.a. for 5 years vs 9.5% p.a. for 10 years.

📝 Question Set 24: Loan EMI Problems

Q166. Loan EMI: P = ₹5,00,000, R = 10% p.a., T = 5 years. Total payment?
Q167. Car loan: P = ₹8,00,000, R = 12% p.a., T = 5 years. Total interest?
Q168. Home loan: P = ₹20,00,000, R = 9% p.a., T = 20 years. Total payment?
Q169. Personal loan: P = ₹3,00,000, R = 15% p.a., T = 3 years. Total cost?
Q170. Education loan: P = ₹10,00,000, R = 8% p.a., T = 10 years. Total payment?

📝 Question Set 25: Savings Problems

Q171. Monthly savings: P = ₹5,000, R = 8% p.a., T = 3 years. Final amount?
Q172. Quarterly savings: P = ₹15,000, R = 10% p.a., T = 4 years. Total amount?
Q173. Yearly savings: P = ₹50,000, R = 12% p.a., T = 3 years. Total interest?
Q174. Daily savings: P = ₹100/day, R = 6% p.a., T = 5 years. Total amount?
Q175. Bi-weekly savings: P = ₹2,500, R = 8% p.a., T = 2 years. Total amount?

🧮 Type 6: Advanced Problem Solving (Questions - 201 to 300)

📝 Question Set 26: Mixed Problems

Q201. ₹1,00,000 split between A at 10% and B at 12% for 2 years, total CI = ₹27,480. Find investments.
Q202. ₹2,00,000 split between three schemes at 8%, 10%, 12% for 3 years, total CI = ₹67,200. Find amounts.
Q203. ₹50,000 split between A and B such that after 2 years, A's amount = B's amount. Rates: 8% and 10%. Find split.
Q204. ₹1,50,000 split between two schemes with CI and SI. After 3 years, total interest = ₹48,000. Find ratio.
Q205. ₹1,00,000 invested at compound rate half-yearly vs simple rate annually. Difference = ₹300 in 2 years. Find rate.

📝 Question Set 27: Time and Rate Problems

Q206. Same amount at compound interest doubles in 4 years. How many years to triple at simple interest?
Q207. Amount becomes triple in 6 years at compound interest. Find approximate rate.
Q208. For how many years will ₹5,000 at 10% p.a. amount to ₹12,100?
Q209. At what rate will ₹10,000 amount to ₹25,000 in 3 years?

Q210. Time required: P = ₹15,000, Amount = ₹24,300, R = 10%.

📝 Question Set 28: Population and Growth

Q211. Population doubles in 10 years. In how many years will it quadruple?

Q212. Population grows at 5% p.a. Current population = 2,000,000. Population in 10 years?

Q213. Bacterial growth: Initial = 1,00,000, Growth rate = 20% per hour. Population in 5 hours?

Q214. City population: 2020 = 5,00,000, Growth = 8% p.a. Population in 2030?

Q215. Country population: 2020 = 10 crores, Growth = 6% p.a. Population in 2035?

📝 Question Set 29: Complex Scenarios

Q216. Investment with varying rates: 10%, 12%, 15%, 8% over 4 years on ₹10,00,000. Final amount?

Q217. Three-year investment with different compounding periods: Year 1 annual, Year 2 half-yearly, Year 3 quarterly.

Q218. Compound vs Simple: ₹1,00,000 at different rates for 3 years, SI = ₹21,000, CI = ₹22,500. Find rate.

Q219. Difference between CI and SI is ₹500 for 2 years at 10% on ₹20,000. Find if compounded annually or half-yearly.

Q220. Effective rate: What rate compounded half-yearly gives same return as 12% annually?

📝 Question Set 30: Challenge Problems

Q221. Find principal if CI for 2 years = ₹6,000 and SI for 2 years = ₹5,400 at 10% p.a.

Q222. If ₹1,000 becomes ₹1,331 in 3 years at compound interest, what will it become in 6 years?

Q223. A sum amounts to ₹16,000 in 2 years and ₹17,600 in 3 years at compound interest. Find principal and rate.

Q224. Find the difference between compound interest and simple interest on ₹8,000 in 2 years at 10% p.a.

Q225. If compound interest for 2 years = ₹4,200 and for 3 years = ₹6,720, find rate and principal.

📝 Question Set 31-32: Advanced Banking

Q226. Tax on interest: FD ₹10,00,000 at 10% for 3 years, tax = 30%. Net amount?

Q227. Inflation effect: Effective return after 5% inflation on 12% investment for 3 years.

Q228. Compound interest with fee: Investment ₹5,00,000, management fee 1%, returns 15% for 2 years.

Q229. Multiple FDs: ₹2,00,000 split in ratio 2:3:5 at 8%, 10%, 12% for 3 years. Total interest?

Q230. Currency conversion: $10,000 at 8% p.a. for 3 years, rate = ₹80/$ initially. Final amount in rupees?

📝 Question Set 33-34: Real Life Applications

Q231. Retirement planning: Invest ₹50,000 every year at 10% p.a. for 30 years. Total amount?

Q232. Education fund: Need ₹20,00,000 in 10 years, invest now at 12% p.a. How much to invest?

Q233. Emergency fund: Save ₹2,000 monthly, investment 8% p.a. for 5 years. Total saved?

Q234. Down payment: Buy car ₹15,00,000 in 3 years, save at 9% p.a. Monthly amount needed?

Q235. House purchase: Loan amount ₹30,00,000, EMI calculation at 8% for 20 years.

📝 Question Set 35: Mathematical Problems

Q236. Find rate if amount after 3 years = ₹20,000, after 4 years = ₹24,200.

Q237. Population doubles in 20 years. When will it be 8 times?

Q238. Compound interest formula: A = P(1 + r)^n. If P = 1, r = 0.1, find n when A = 3.

Q239. Compound interest with continuous compounding: P = 10,000, R = 8%, T = 5 years.

Q240. Find time when amount triples at 15% p.a. compound interest.

📝 Question Set 36: Quick Calculation Tricks

Q241. Find 25% interest in 2 years, what will be first year interest rate?

Q242. If amount doubles in 6 years at compound interest, find amount in 18 years.

Q243. Find effective rate of 20% p.a. compounded half-yearly for 3 years.

Q244. Compound interest with monthly deposits: ₹5,000/month at 12% p.a. for 2 years.

Q245. Find the ratio of amounts for different time periods at same rate.

📝 Question Set 37: Advanced Problems

Q246. Compound interest with changing rates each month for 1 year.

Q247. Find principal if CI for 3 years = ₹40,000 and CI for 4 years = ₹44,000 at same rate.

Q248. Population with emigration: Growing at 5% but losing 2% annually.

Q249. Compound interest with tax deduction each year at 30% rate.

Q250. Investment with withdrawal each year: P = ₹5,00,000, withdraw ₹50,000 annually at 10% interest.

📝 Question Set 38: Specialized Problems

Q251. Compound interest with half-yearly compounding but different rates each half-year.

Q252. Find rate if ₹1 becomes ₹2 in 10 years at compound interest.

Q253. Compound vs Simple: Difference is ₹50 for 2 years at 5% on P. Find P.

Q254. Effective rate comparison: Annual 12% vs semi-annual compound rate.

Q255. Compound interest with decreasing principal each year.

📝 Question Set 39-40: Mixed Applications

Q256. Car depreciation: Value decreases 10% annually for 3 years from ₹20,00,000.

Q257. Medical inflation: 8% p.a. for healthcare costs, current cost ₹1,00,000.

Q258. Gold investment: Price increases 12% annually, invest now ₹5,00,000.

Q259. Stock market: 15% growth with 2% dividend annually.

Q260. Education inflation: 10% p.a., current fees ₹1,00,000 per year.

📝 Question Set 41-42: Final Challenge

Q261. Complex investment: Multiple schemes with different rates and compounding periods.

Q262. Retirement portfolio: Mix of FD, stocks, mutual funds with different returns.

Q263. Loan restructuring: Original loan at 10%, restructured at 12% after 2 years.

Q264. Investment with quarterly deposits and annual compounding.

Q265. Find effective annual rate for varying quarterly rates.

📝 Question Set 43-50: Ultimate Problems

Q266. Compound interest with changing compounding frequency over time.

Q267. Find sum if CI for 3 years = ₹33,100 and for 4 years = ₹39,720.

Q268. Population with birth and migration: Birth rate 8%, net migration 2%.

Q269. Investment with withdrawal and deposit each year at different rates.

Q270. Effective rate comparison across different investment options.

📝 Question Set 51-60: Advanced Scenarios

Q271. Compound interest with variable rates each quarter for 2 years.

Q272. Investment with compound interest and compound inflation.

Q273. Find time when compound interest equals simple interest.

Q274. Multiple rate changes: 8% for 1 year, 10% for 2 years, 12% for 3 years.

Q275. Compound interest with changing principal each year.

📝 Question Set 61-70: Professional Level

Q276. Financial planning: Multiple goals with different timelines and rates.

Q277. Investment with compound interest and tax implications.

Q278. Find rate if given multiple time-amount pairs.

Q279. Compound interest with different compounding for different periods.

Q280. Real estate investment with appreciation and rental income.

📝 Question Set 71-80: Expert Problems

Q281. Compound interest with changing compounding periods.

Q282. Investment with compound interest and periodic withdrawals.

Q283. Find effective annual rate for varying nominal rates.

Q284. Compound interest with partial withdrawals each year.

Q285. Multiple investments with different compounding frequencies.

📝 Question Set 81-90: Mastery Level

Q286. Compound interest with changing rates and compounding.

Q287. Financial mathematics: Compound interest with inflation.

Q288. Find principal given complex interest patterns.

Q289. Compound interest with tax and inflation effects.

Q290. Advanced investment strategies with compound growth.

📝 Question Set 91-100: Final Challenge

Q291. Compound interest with changing conditions over time.

Q292. Complex financial scenarios with multiple variables.

Q293. Find rate from complex time-amount relationships.

Q294. Compound interest with varying parameters annually.

Q295. Ultimate compound interest problem with all variables changing.

📝 Question Set 101-110: Beyond Basics

Q296. Compound interest with advanced financial concepts.

Q297. Investment with compound growth and complex withdrawals.

Q298. Financial modeling with compound interest variations.

Q299. Complex scenarios with multiple investment options.

Q300. Comprehensive problem solving with all compound interest concepts.

🎯 Important Formulas Summary

Standard Compound Interest:
Amount = P × (1 + R/100)ⁿ
CI = Amount - Principal

Different Compounding Periods:
Half-yearly: Amount = P × (1 + R/200)²ⁿ
Quarterly: Amount = P × (1 + R/400)⁴ⁿ
Monthly: Amount = P × (1 + R/1200)¹²ⁿ

Effective Rate:
Effective Rate = [(1 + R/100)ⁿ - 1] × 100

SI-CI Difference:
CI - SI = P × (R/100)² × (3n - 2)/2n for 3 years
CI - SI = P × (R/100)² for 2 years

💡 Quick Tricks for Competitive Exams

🎯 Speed Math Tricks:
• 10% in 1 year = 1.1 multiplier
• 20% in 2 years = 1.21 multiplier
• 25% in 2 years = 1.5625 multiplier
• 12% half-yearly effective = 12.36%
• 2 years CI-SI difference = P(R/100)²

📋 Previous Year Questions Pattern

Year Question Type Marks

2023 Mixed rates CI 5

2022 Time calculation CI 8

2021 Banking CI problem 10

2020 Population growth CI 12

🏆 Final Advice for Success

🎯 Study Strategy:
• Practice 50+ questions daily
• Focus on speed and accuracy
• Learn shortcut methods
• Master formulas thoroughly
• Solve previous year papers
• Time management in exam
📅 Daily Plan:
• 20 basic questions
• 15 medium level questions
• 10 advanced questions
• 5 previous year questions

🚀 Your Success Formula:
Practice + Speed + Accuracy = Success in CI Questions
Remember: Compound Interest is a scoring chapter if you practice well!
Best of Luck! 📚🎯

Year	Question Type	Difficulty
2023	Simple CI with different rates	Easy
2022	Time calculation using logs	Medium
2021	CI vs SI difference problem	Easy-Medium
2020	Population growth problem	Medium
2019	Effective rate calculation	Hard

Year	Question Type	Marks
2023	Mixed rates CI	5
2022	Time calculation CI	8
2021	Banking CI problem	10
2020	Population growth CI	12

Thursday, 12 March 2026