Pariksha SaathiQuantitative Aptitude
Simple and Compound Interest: Practice Questions with Answers
15 practice questions on Simple and Compound Interest, with answers; most also have an explanation or a worked solution. Try each one before you open its answer.
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Q.1
Find the difference between the compound interest and simple interest on ₹15,000 for 2 years at 10% per annum.
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Answer: ₹150
Solution:
- SI = (15,000 × 10 × 2) / 100 = 3,000
- CI: Amount = 15,000 × (1.10)² = 15,000 × 1.21 = 18,150, so CI = 3,150
- Difference = 3,150 − 3,000 = 150
- Shortcut check: P × (R/100)² = 15,000 × 0.01 = 150 — matches, for 2 years only.
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Q.2
Find the difference between the compound interest and simple interest on ₹8,000 for 3 years at 5% per annum.
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Answer: ₹61
Solution:
- SI = (8,000 × 5 × 3) / 100 = 1,200
- CI: Amount = 8,000 × (1.05)³ = 8,000 × 1.157625 = 9,261, so CI = 1,261
- Difference = 1,261 − 1,200 = 61
- Shortcut check: P × (R/100)² × (3 + R/100) = 8,000 × 0.0025 × 3.05 = 20 × 3.05 = 61 — matches.
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Q.3
Find the compound interest on ₹10,000 for 2 years at 10% per annum, compounded annually.
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Answer: ₹2,100
Solution:
- Amount = 10,000 × (1.10)²
- = 10,000 × 1.21 = 12,100
- CI = 12,100 − 10,000 = 2,100
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Q.4
A sum of ₹8,000 amounts to ₹9,440 in 3 years at simple interest. Find the rate of interest per annum.
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Answer: 6% per annum
Solution:
- SI = 9,440 − 8,000 = 1,440
- R = (SI × 100) / (P × T) = (1,440 × 100) / (8,000 × 3)
- = 144,000 / 24,000 = 6%
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Q.5
Find the simple interest on ₹5,000 at 8% per annum for 3 years.
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Answer: ₹1,200
Solution:
- SI = (P × R × T) / 100
- = (5,000 × 8 × 3) / 100
- = 1,200
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Q.6
A sum invested at 20% per annum, compounded annually, earns a compound interest of ₹1,760 in 2 years. Find the sum.
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Answer: ₹4,000
Solution:
- Over 2 years at 20%, the amount factor is (1.20)² = 1.44, so CI is 0.44 of the principal.
- 0.44 × P = 1,760
- P = 1,760 / 0.44 = 4,000
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Q.7
₹5,000 is invested for 2 years with a rate of 10% in the first year and 20% in the second year, compounded annually. Find the compound interest earned.
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Answer: ₹1,600
Solution:
- Amount = 5,000 × 1.10 × 1.20 (multiply each year's factor; do not average the two rates)
- = 5,000 × 1.32 = 6,600
- CI = 6,600 − 5,000 = 1,600
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Q.8
Find the compound interest on ₹12,000 at 10% per annum for 2 years and 6 months, compounded annually.
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Answer: ₹3,246
Solution:
- Amount after the first 2 whole years = 12,000 × (1.10)² = 12,000 × 1.21 = 14,520.
- For the remaining 6 months (0.5 year), add simple interest on this amount: SI = 14,520 × 10 × 0.5 / 100 = 726.
- Final amount = 14,520 + 726 = 15,246. CI = 15,246 − 12,000 = 3,246.
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Q.9
Find the compound interest on ₹20,000 for 2 years at 5% per annum, compounded annually.
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Q.10
A sum amounts to ₹6,600 in 4 years at 5% simple interest per annum. Find the principal.
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Q.11
Find the difference between the compound interest and simple interest on ₹4,000 for 3 years at 10% per annum.
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Q.12
₹2,000 is invested for 2 years at 25% in the first year and 10% in the second, compounded annually. Find the compound interest.
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Q.13
A sum of ₹1,600 earns a compound interest of ₹900 in 2 years, compounded annually. Find the rate of interest.
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Answer: 25%. (1 + R/100)² = 1 + 900/1,600 = 1.5625 = 1.25², so R = 25.
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Q.14
Find the compound interest on ₹10,000 at 10% per annum for 1 year 6 months, compounded annually (using the standard fractional-year convention).
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Answer: ₹1,550. Amount after 1 year = 11,000; SI on 11,000 for 0.5 year at 10% = 550; total CI = 1,000 + 550.
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Q.15
Find the simple interest on ₹12,000 at 5% per annum for 4 years.
How these questions were made
Written by Mahesh Srivastava, Founder of Pariksha Saathi. Published: 2026-10-01.