All Exams Quantitative Aptitude: Simple & Compound Interest — Complete Concept Guide with MCQs

Exam: All Exams | Subject: Quantitative Aptitude | Topic: Simple & Compound Interest | Year: 2026

Concept Overview

Simple and Compound Interest is one of the highest-scoring topics in SSC Quantitative Aptitude. Questions range from direct formula application to multi-step problems involving rate finding, time calculation, and difference between CI and SI.

Essential Formulas

  • Simple Interest: SI = (P × R × T) / 100
  • Amount (SI): A = P + SI = P(1 + RT/100)
  • Compound Interest: A = P(1 + R/100)^T; CI = A - P
  • CI-SI Difference (2 years): CI - SI = P(R/100)²
  • CI-SI Difference (3 years): CI - SI = P(R/100)²(3 + R/100)
  • Doubling Time (SI): T = 100/R years
⚡ Quick Shortcut: For 2-year CI at rate r%, effective rate = r + r + r²/100. Example: 10% for 2 years → effective = 10+10+1 = 21%. So ₹1000 gives CI of ₹210. This saves calculation time in exams!

Practice MCQs (10 Questions)

Test your understanding of Simple & Compound Interest with these All Exams level questions.

Q1. Simple Interest on ₹5000 at 8% per annum for 3 years is:

  1. ₹1200
  2. ₹1300
  3. ₹1100
  4. ₹1400

Explanation: SI = (P × R × T)/100 = (5000 × 8 × 3)/100 = 1,20,000/100 = ₹1200. Straightforward formula application.

Q2. What is the compound interest on ₹10000 at 10% for 2 years?

  1. ₹2100
  2. ₹2000
  3. ₹2200
  4. ₹1900

Explanation: CI = P(1+r/100)^t - P = 10000(1.1)² - 10000 = 10000 × 1.21 - 10000 = 12100 - 10000 = ₹2100.

Q3. At what rate will ₹800 double itself in 10 years (Simple Interest)?

  1. 10%
  2. 8%
  3. 12%
  4. 5%

Explanation: For SI to double: SI = P, so P = PRT/100 → 1 = RT/100 → R = 100/T = 100/10 = 10%.

Q4. The difference between CI and SI for 2 years at 5% on ₹8000 is:

  1. ₹20
  2. ₹25
  3. ₹15
  4. ₹30

Explanation: For 2 years, CI - SI = P(r/100)² = 8000 × (5/100)² = 8000 × 0.0025 = ₹20. Key formula to memorize!

Q5. Sum that gives ₹540 as SI in 3 years at 9% per annum:

  1. ₹2000
  2. ₹1800
  3. ₹2500
  4. ₹1500

Explanation: SI = PRT/100 → 540 = P × 9 × 3/100 → P = 54000/27 = ₹2000.

Q6. CI on ₹25000 at 4% per annum for 2 years (compounded annually):

  1. ₹2040
  2. ₹2000
  3. ₹2080
  4. ₹1960

Explanation: CI = 25000(1.04)² - 25000 = 25000 × 1.0816 - 25000 = 27040 - 25000 = ₹2040.

Q7. Simple Interest on ₹5000 at 8% per annum for 3 years is:

  1. ₹1200
  2. ₹1300
  3. ₹1100
  4. ₹1400

Explanation: SI = (P × R × T)/100 = (5000 × 8 × 3)/100 = 1,20,000/100 = ₹1200. Straightforward formula application.

Q8. What is the compound interest on ₹10000 at 10% for 2 years?

  1. ₹2100
  2. ₹2000
  3. ₹2200
  4. ₹1900

Explanation: CI = P(1+r/100)^t - P = 10000(1.1)² - 10000 = 10000 × 1.21 - 10000 = 12100 - 10000 = ₹2100.

Q9. At what rate will ₹800 double itself in 10 years (Simple Interest)?

  1. 10%
  2. 8%
  3. 12%
  4. 5%

Explanation: For SI to double: SI = P, so P = PRT/100 → 1 = RT/100 → R = 100/T = 100/10 = 10%.

Q10. The difference between CI and SI for 2 years at 5% on ₹8000 is:

  1. ₹20
  2. ₹25
  3. ₹15
  4. ₹30

Explanation: For 2 years, CI - SI = P(r/100)² = 8000 × (5/100)² = 8000 × 0.0025 = ₹20. Key formula to memorize!

Key Takeaways

  • Master the core concepts and formulas for Simple & Compound Interest before attempting questions
  • Practice elimination strategy — rule out clearly wrong options first
  • Review explanations for every question, including those you answered correctly
  • This topic appears consistently in All Exams exams — expect 2-4 questions

Prepared for All Exams 2026 examination by GPT Sir. Visit gptsir.in for more practice material and AI-powered study assistance.