Simple & Compound Interest

LSSSSB Non-Technical · Mathematics · 49 practice questions with answers and explanations: 21 Easy, 27 Medium, 1 Hard.

Sample questions

Sample Easy question 1

At what rate of simple interest per annum will Rs. 8000 amount to Rs. 8960 in 2 years?

  1. 6%
  2. 8%
  3. 7%
  4. 5%
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Answer: A. Simple interest = 8960 − 8000 = Rs. 960. Rate = (960 × 100) ÷ (8000 × 2) = 6%.

Sample Easy question 2

At what rate of simple interest per annum will Rs. 12000 amount to Rs. 15000 in 5 years?

  1. 5%
  2. 4%
  3. 6%
  4. 7%
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Answer: A. Simple interest = 15000 − 12000 = Rs. 3000. Rate = (3000 × 100) ÷ (12000 × 5) = 5%.

Sample Easy question 3

Find the simple interest on Rs. 2000 at 6% per annum for 3 years.

  1. 400
  2. 360
  3. 330
  4. 300
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Answer: B. SI = (2000 × 6 × 3)/100 = 360.

Sample Medium question 4

In how many years will a sum become triple itself at 10% simple interest per annum?

  1. 20 years
  2. 18 years
  3. 15 years
  4. 22 years
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Answer: A. For the sum to triple, SI = 2P. Time = (2P×100)/(P×10) = 20 years.

Sample Medium question 5

Find the compound interest on Rs. 1000 for 1 year at 10% per annum, compounded half-yearly.

  1. 105
  2. 100
  3. 102.5
  4. 100.5
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Answer: C. Half-yearly rate = 5%, for 2 periods: Amount = 1000×(1.05)² = 1102.5. CI = 102.5.

Sample Medium question 6

A sum of Rs. 8000 becomes Rs. 9261 in 3 years at compound interest, compounded annually. Find the rate of interest.

  1. 7%
  2. 4%
  3. 5%
  4. 6%
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Answer: C. 9261/8000 = (1+r/100)³. Taking the cube root: 1+r/100 = 1.05, so r = 5%.

Sample Hard question 7

Find the compound interest on Rs. 10,000 for 1.5 years at 10% per annum, compounded half-yearly.

  1. 1600
  2. 1576.25
  3. 1500
  4. 1550
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Answer: B. With 5% per half-year over 3 periods, amount = 10000 × 1.05³ ≈ 11576.25, so CI ≈ 1576.25.

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