Simple & Compound Interest – Basic Formulas
SSC GD Exam Preparation - Quantitative Aptitude
🔹 1. Simple Interest (SI)
Simple Interest is interest calculated uniformly every year on the principal.
Formula:
SI = (P × R × T) / 100
Amount (A):
A = P + SI
Where:
P = Principal
R = Rate (%) per annum
T = Time (years)
🔹 2. Compound Interest (CI)
Compound Interest is interest calculated on principal + accumulated interest.
A. When compounded yearly
A = P(1 + R/100)T
CI = A - P
B. When compounded half-yearly
Rate becomes R/2, Time becomes 2T
A = P(1 + R/200)2T
C. When compounded quarterly
Rate = R/4, Time = 4T
A = P(1 + R/400)4T
D. Difference between CI and SI (for 2 years)
CI - SI = P(R/100)2
E. Difference for 3 years
CI - SI = P × (R/100)2 × (3 + R/100)
🧠Practice Section: 15 Practice Questions (With Answers)
Test your Simple & Compound Interest concepts with these SSC GD level practice questions. Click on "View Answer" to check your understanding.
Q1. Find SI on ₹5000 at 8% for 2 years.
View Answer
SI = (5000×8×2)/100 = ₹800
Q2. Find amount when P = ₹4000, R = 10%, T = 3 years (SI).
View Answer
SI = (4000×10×3)/100 = ₹1200, Amount = 4000 + 1200 = ₹5200
Q3. Find CI on ₹2000 at 10% for 2 years (Yearly).
View Answer
A = 2000(1+0.10)² = 2000 × 1.21 = ₹2420, CI = 2420 − 2000 = ₹420
Q4. Find CI on ₹5000 at 8% for 1 year (yearly).
View Answer
A = 5000 × 1.08 = ₹5400, CI = 5400 − 5000 = ₹400
Q5. If SI for 3 years at 5% is ₹750, find P.
View Answer
SI = (P×5×3)/100 = 750, P = 75000/15 = ₹5000
Q6. If P = ₹6000, R = 12%, SI for 1 year = ?
View Answer
SI = (6000×12×1)/100 = ₹720
Q7. Find CI on ₹8000 at 5% for 2 years.
View Answer
A = 8000 × (1.05)² = 8000 × 1.1025 = ₹8820, CI = 8820 − 8000 = ₹820
Q8. Rate = 10%, T = 2 years, CI − SI on ₹5000 = ?
View Answer
Difference = P(R/100)² = 5000(0.10²) = 5000×0.01 = ₹50
Q9. Find time if P=₹4000, SI=₹800, R=5%.
View Answer
T = SI×100 / (P×R) = 800×100/(4000×5) = 4 years
Q10. A sum becomes ₹1150 in 2 years at SI @5%. Find principal.
View Answer
Let P = x, SI = (x×5×2)/100 = 0.1x, x + 0.1x = 1150, 1.1x = 1150, x = ₹1045.45
Q11. CI on ₹10000 at 10% for 1 year (half-yearly).
View Answer
Rate = 10/2 = 5%, Time = 2 periods, A = 10000(1.05)² = 10000 × 1.1025 = ₹11025, CI = ₹1025
Q12. CI on ₹1600 at 5% for 2 years.
View Answer
A = 1600 × 1.1025 = ₹1764, CI = ₹164
Q13. Find SI on ₹2500 at 6% for 4 years.
View Answer
SI = (2500×6×4)/100 = ₹600
Q14. A sum doubles itself in 10 years at SI. Find rate.
View Answer
Double → SI = P, SI = PRT/100, P = P×R×10/100, R = 10%
Q15. If CI for 2 years on ₹5000 at R% is ₹1025, find R.
View Answer
A = 5000 + 1025 = 6025, (1+R/100)² = 6025/5000 = 1.205, 1+R/100 = √1.205 ≈ 1.098, R ≈ 9.8%
✅ SSC GD Exam Strategy
🟢 Memorize SI and CI formulas for quick calculations
🟢 Practice different compounding periods (yearly, half-yearly, quarterly)
🟢 Master CI-SI difference formulas for 2 and 3 years
🟢 Learn to quickly find principal, rate, or time from given values
🟢 Time yourself - aim for 45-60 seconds per interest question
You've completed Simple & Compound Interest Concepts!
SSC GD Tip: Simple & Compound Interest are fundamental topics that frequently appear in competitive exams. Focus on mastering the basic formulas and understanding the key differences between SI and CI. Remember that compound interest grows faster due to interest on interest. Practice different compounding frequencies and the CI-SI difference formulas as they are commonly tested. Regular practice with previous year SSC GD questions will build your speed and accuracy in solving interest problems efficiently.
Master Simple & Compound Interest for SSC GD Exam!
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