Quantitative Aptitude

Simple and Compound Interest

3,394 Questions
All Simple interest and its inverse forms 768 Compound interest with annual compounding 742 Simple-interest growth and split sums 626 Difference between compound and simple interest 479 Half-yearly and quarterly compounding 252 Changing rates and fractional years 201 Installments (CI based) 190 Ratio of principal to interest 118 Population growth and depreciation 16

Simple and Compound Interest Questions

Multiple choice

A sum of money doubles itself in 4 years at compound interest. It will amount to 8 times of itself at the same rate of interest in-

  1. 16 years

  2. 6 years

  3. 8 years

  4. 12 years
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

If money doubles in 4 years at compound interest, then 2x = x(1+r)^4, so (1+r)^4 = 2. For 8 times: 8x = x(1+r)^n. Since 8 = 2^3, we have 2^3 = ((1+r)^4)^3 = (1+r)^12. Therefore n = 12 years. Option C (8 years) is a common mistake using simple interest logic. Option B (6 years) and A (16 years) don't satisfy the exponential relationship.

Multiple choice

What will be the compound interest on an amount of Rs. 7500 at the rate of interest 16% for 3 years compounded annually ?

  1. 4260.7

  2. 4206.72

  3. 4602.76

  4. 4260.76

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Principal P = Rs. 7500, Rate R = 16%, Time n = 3 years. Amount A = P(1 + R/100)³ = 7500(1 + 0.16)³ = 7500(1.16)³. Calculating: 1.16³ = 1.16 × 1.16 × 1.16 = 1.3456 × 1.16 ≈ 1.5609. So A ≈ 7500 × 1.5609 = Rs. 11706.72. Compound Interest CI = A - P = 11706.72 - 7500 = Rs. 4206.72.

Multiple choice

What will be compound interest obtained on an amount of Rs. 8800 at 5 p.c.p.a. after 3 years?

  1. Rs. 1329.20

  2. Rs. 1348.75

  3. Rs. 1335.26

  4. Rs. 1387.10

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Compound Interest formula: A = P(1 + r/100)ⁿ. Here P = 8800, r = 5%, n = 3. A = 8800 × (1.05)³ = 8800 × 1.157625 = Rs. 10187.10. CI = A - P = 10187.10 - 8800 = Rs. 1387.10. Option A (1329.20) would be the simple interest for 3 years at 5%. Option B and C are incorrect calculations.

Multiple choice

The questions given below contain three statements giving certain data. You have to decide whether the data given in the statements are sufficient for answering the question? What is the rate of interest per year? I. C.I. is Rs. 94 after 2 years. II. S.I. is Rs. 83 on the same sum after two years. III. Sum is Rs. 440

  1. From statement I and III

  2. From statement II and III

  3. From statement I and II

  4. From statement I and II or statement II and III or statement I and III

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Any two of the three statements are sufficient. Using I and III: CI = P(1+r/100)^2 - P = 94, with P=440 gives r. Using II and III: SI = (P×r×2)/100 = 83, with P=440 gives r. Using I and II: CI - SI = 94 - 83 = 11, and using the relationship between CI and SI for 2 years, we can find r. All combinations work.

Multiple choice

A sum doubles itself in 16 years, then in how many years will it triple itself, rate of interest being simple.

  1. 32 years

  2. 24 years

  3. 48 years

  4. 64 years
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If a sum doubles in 16 years at simple interest, then the interest equals the principal in 16 years. So rate = (100% / 16) = 6.25% per year. To triple the sum, we need 200% interest (principal + 100% more). Time needed = 200% / 6.25% = 32 years. Alternatively, doubling time × 2 = 16 × 2 = 32 years for triple at simple interest.

Multiple choice

Any amount becomes 500 in 4 years at the rate of compound interest and becomes 800 in 8 years then what is the principal ?

  1. 320.50

  2. 291.50

  3. 312.50

  4. 340.50

  5. 325.20
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In compound interest, if amount becomes 500 in 4 years and 800 in 8 years, let principal be P and rate be r%. Then P(1 + r/100)⁴ = 500 and P(1 + r/100)⁸ = 800. Dividing: (1 + r/100)⁴ = 800/500 = 1.6. So P × 1.6 = 500, therefore P = 500/1.6 = 312.5. This is option C.

Multiple choice

A sum of money at compound interest will amount to Rs. 650 at the end of the first year and Rs. 676 at the end of the second year. The amount of money is-

  1. Rs. 1300

  2. Rs. 650

  3. Rs. 1250

  4. Rs. 625

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

If amount grows from Rs. 650 to Rs. 676 in one year, the interest rate = (676-650)/650 = 26/650 = 0.04 or 4%. Since this is compound interest, the principal for first year = 650/1.04 = Rs. 625. Option D is correct.

Multiple choice

The compound interest earned on an amount of Rs 15000 at the end of 3 years is Rs 3895.68. What is the rate of interest p.c.p.a?

  1. 7%

  2. 10%

  3. 8%

  4. 6%

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

8% is correct. Using compound interest formula: Amount = Principal × (1 + r)^n. So 15000 + 3895.68 = 15000 × (1 + r)^3. Therefore 18895.68/15000 = (1 + r)^3. 1.259712 = (1 + r)^3. Taking cube root: 1.08 = 1 + r. So r = 0.08 = 8%. This requires working backwards from CI amount to find the rate.

Multiple choice

Find the compound interest for Rs.50000 for 3 years ,while the interest rate for first year is 10% , second year is 11% and for third year is 12%?
  1. $18376 Rs.$
  2. $14000 Rs$
  3. $15312 Rs$
  4. $16972 Rs$

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For varying interest rates, apply them sequentially to the amount. After Year 1: 50000 × 1.10 = 55000. After Year 2: 55000 × 1.11 = 61050. After Year 3: 61050 × 1.12 = 68376. Compound Interest = 68376 - 50000 = 18376. The claimed answer A is correct.

Multiple choice

The simple interest earned on a certain principal in 5 years @12% per annum is Rs.1536. What amount of simple interest would a man get if he invests Rs. 1000 more than the previous principal for 2 years at the same rate of S.I. ?

  1. Rs 238.40

  2. Rs 854.40

  3. Rs 676.40

  4. Rs 45.24
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

SI = P × R × T / 100. First: P × 12 × 5 / 100 = 1536, so P = 1530 × 100 / 60 = 2560. New principal = 2560 + 1000 = 3560. SI = 3560 × 12 × 2 / 100 = 854.40.