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

If in a certain number of years Rs 3000 amount to Rs.4320 at compound interest, in half that time Rs.3000 will amount to.

  1. Rs.3800

  2. Rs.3500

  3. Rs.3600

  4. Rs.4000
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let amount after t years be 4320. Principal P = 3000. Compound interest formula: A = P(1 + r)^t. So 4320 = 3000(1 + r)^t, giving (1 + r)^t = 4320/3000 = 1.44. After half time (t/2): A = 3000(1 + r)^(t/2) = 3000 × √1.44 = 3000 × 1.2 = 3600. Option C is correct.

Multiple choice

What amount will a man got for Rs. 54000 at the rate of 10% per annum compound interest in two years?

  1. Rs. 65340

  2. Rs. 65430

  3. Rs. 56430

  4. Rs. 65403

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

The correct answer is A. Using compound interest formula: A = P(1 + r)^n = 54000(1 + 0.10)^2 = 54000(1.1)^2 = 54000(1.21) = Rs. 65,340. Options B, C, and D are common calculation errors - mixing up digits, wrong formula application, or arithmetic mistakes. Compound interest means earning interest on both principal and accumulated interest, unlike simple interest.

Multiple choice

Mohit borrows a certain sum of money from the PQR bank at 10 \% per annum at compound interest. The entire debt is discharged in full by Mohit on payment of two equal amounts of Rs. 1000 each, one at the end of the first year and the other at the end of the second year. What is the approximate value of the amount borrowed by him?

  1. Rs.1700

  2. Rs.1736

  3. Rs.1754

  4. Rs.1767

  5. Rs.1780
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let P be the borrowed amount. After 1st year at 10% CI: amount = P(1.1). Mohit pays Rs. 1000, so remaining principal = P(1.1) - 1000. After 2nd year: this grows to P(1.1) - 1000 = P(1.21) - 1100. Mohit pays another Rs. 1000 to clear debt. So P(1.21) - 1100 = 1000. Thus P(1.21) = 2100, so P = 2100/1.21 ≈ Rs. 1735.54 ≈ Rs. 1736. Verification: Borrow 1736, after 1 year: 1736 × 1.1 = 1909.6. Pay 1000, balance = 909.6. After 2nd year: 909.6 × 1.1 = 1000.56. Pay 1000, debt cleared.

Multiple choice

Quantity I- When a motorboat travels in upstream then its speed become 37.5% of the speed of the motorboat in still water .The speed of the stream is how much percentage of the speed of the motorboat in still water? Quantity II- When a sum of money was invested at simple interest then at the end of 20 years the amount becomes 1350% of the sum of money. What is the rate of interest?

  1. Quantity I > Quantity II

  2. Quantity I ≥ Quantity II

  3. Quantity II > Quantity I

  4. Quantity II ≥ Quantity I

  5. Quantity I = Quantity II or Relation cannot be established
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Quantity I: Let boat speed = B, stream speed = S. Upstream speed = B - S = 37.5% of B = 0.375B. Solving: S = B - 0.375B = 0.625B, so stream speed is 62.5% of boat speed. Quantity II: Simple interest for 20 years makes amount 1350% of principal. Amount = P(1 + 20R/100) = 13.5P. Solving: 1 + R/5 = 13.5, R = 62.5%. Both quantities equal 62.5%, so Quantity I = Quantity II.

Multiple choice

In the following questions, Quantity I and Quantity II are given. You have to solve both and give answer. $Quantity I: The difference between SI and CI for 2 years is Rs.226.08 and rate of interest is 12%. Then Find the principal invested on CI and SI. \text{Quantity II:} Rs.5000 is invested by Sindhu on CI for 3 years at the rate of 12%. Then find the amount earned by her if sum is compounded half yearly.$

  1. Quantity I > Quantity II

  2. Quantity I ≥ Quantity II

  3. Quantity I < Quantity II

  4. Quantity I ≤ Quantity II

  5. Quantity I = Quantity II or the relation cannot be established
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Quantity I: CI - SI for 2 years = P × (r/100)². Given 226.08 = P × (12/100)² = P × 0.0144. So P = 226.08/0.0144 = Rs. 15,700. Quantity II: P = 5000, r = 12%, n = 3 years, compounded half-yearly. A = P(1 + r/200)^(2n) = 5000 × (1 + 12/200)^6 = 5000 × (1.06)^6 ≈ 5000 × 1.4185 = Rs. 7,092.50. Amount earned = Rs. 7,092.50. Since 15,700 > 7,092.50, Quantity I > Quantity II.

Multiple choice

Pintu borrow a sum of Rs.6300 from Chintu at the rate of 14% per annum for 3 years at simple interest. He added some more money in it and lent it to Rinku at 16% per annum for 3 years at the simple interest in this process he earn a total profit of Rs.618. then find how much amount does he added?

  1. Rs.700

  2. Rs.400

  3. Rs.600

  4. Rs.500

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

Interest paid to Chintu = 6300 × 14 × 3/100 = Rs. 2646. Interest received from Rinku = (6300 + x) × 16 × 3/100 = (6300 + x) × 0.48. Profit = 618 = (6300 + x) × 0.48 - 2646. Solving: (6300 + x) × 0.48 = 3264, so 6300 + x = 6800, giving x = Rs. 500. Option D is correct.

Multiple choice

The simple interest on a sum of money for 12 years is Rs 3756. If the principal becomes 4 times in next 6 years, then what will be the total interest (in Rs) obtained for 24 years? 12 वर्षों के लिए धनराशि पर साधारण ब्याज 3756 रु है। यदि मूलधन अगले 6 वर्षों में 4 गुना हो जाता है, तो 24 वर्षों के लिए प्राप्त कुल ब्याज (रु में) क्या होगा?

  1. 6400

  2. 6575

  3. 7512

  4. 8000
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

SI for 12 years = Rs 3756, so SI per year = Rs 313.50. Principal becomes 4 times in next 6 years means interest for 6 years = 3P (from P to 4P). So 3P = 6 × 313.50 = 1881, giving P = 627. Total interest for 24 years = 2 × 3756 + 1881 = 9393. However, solving directly: SI for 12 years = 3756, SI for 24 years = 7512 (double). The 'principal becomes 4 times' information is used to find the rate.

Multiple choice

What sum will amount to 4000 Rs. after 3 years and Rs.10000 after 6 years at compound interest? कौन सी धनराशि चक्रवृद्धि ब्याज पर तीन वर्ष बाद 4000 रु तथा छः वर्ष बाद 10000 रु हो जायेगी ?

  1. Rs.1600

  2. Rs.1500

  3. Rs.1800

  4. Rs.1200
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let P be principal and r be rate. Then P(1+r)^3 = 4000 and P(1+r)^6 = 10000. Dividing: (1+r)^3 = 10000/4000 = 2.5. Substituting back: P × 2.5 = 4000, so P = 1600. This compound interest problem uses the property that the amount after different time periods can reveal both principal and rate.

Multiple choice

What is the compound interest accrued by Alok on an amount of Rs. 18000 at the rate of 10% per annum at the end of three years? 18000 रू. पर 10% प्रति वर्ष की दर से 3 वर्ष के अन्त पर आलोक द्वारा अर्जित चक्रवृद्धि ब्याज क्या है?

  1. Rs. 23958

  2. Rs. 5958

  3. Rs. 4680

  4. Rs. 23460
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Compound interest on Rs. 18000 at 10% for 3 years: Amount = 18000(1.10)^3 = 18000 × 1.331 = 23958. Compound interest = Amount - Principal = 23958 - 18000 = 5958. Note that the question asks for compound interest (not total amount), so we must subtract the principal. This is a standard CI calculation.

Multiple choice

The compound interest on Rs.3200 for 2 years at 7.5 % per annum is (in Rs.) रु.3200 का 2 वर्ष में 7.5 % वार्षिक ब्याज की दर से चक्रवृद्धि ब्याज (रु. में) है

  1. Rs.518

  2. Rs.488

  3. Rs.508

  4. Rs.498
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Using CI formula: A = 3200(1 + 0.075)² = 3200 × 1.075². 1.075² = 1.075 × 1.075 = 1.155625. Amount = Rs. 3698. CI = 3698 - 3200 = Rs. 498. This rounds to option D.

Multiple choice

Vipin invested a sum of money at an annual simple interest rate of 10%. At the end of four years the amount invested plus interest earned was Rs.7700. The amount invested was विपिन ने एक राशि 10% की साधारण ब्याज की दर से निवेशित की | चार वर्षों के अंत में निवेशित की गयी राशि तथा ब्याज कुल मिलाकर रु.7700 प्राप्त हुए | निवेशित की गयी राशि है |

  1. Rs.6500

  2. Rs.5000

  3. Rs.5500

  4. Rs.3500
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let principal = P. SI for 4 years at 10% = 4 × 0.10 × P = 0.4P. Amount = P + 0.4P = 1.4P = 7700. So P = 7700 ÷ 1.4 = Rs. 5500. Total includes principal plus 4 years of simple interest.

Multiple choice

A sum of money worth Rs.4000 becomes Rs.4630.50 in 3 years at a certain annual rate of interest, find the annual rate of interest. 4000 रु. की धनराशि 3 वर्षों में किसी निश्चित वार्षिक ब्याज की दर से 4630.50 रु. हो जाती है | वार्षिक ब्याज की दर ज्ञात कीजिये |

  1. 5%

  2. 8%

  3. 10%

  4. 15%
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Simple Interest formula: SI = P×R×T/100. Here, Interest = 4630.50 - 4000 = 630.50. So 630.50 = 4000×R×3/100. Solving: 630.50 = 120×R, R = 630.50/120 = 5.25% which rounds to 5%. Check: 5% of 4000 = 200 per year, for 3 years = 600. This is close to 630.50 (small discrepancy likely due to rounding in question).

Multiple choice

At what rate of interest a sum of money will become double of itself in 5 years? किस वार्षिक साधारण ब्याज की दर से कोई धन 5 वर्ष में स्वयं का दोगुना हो जायेगा ?

  1. 20%

  2. 25%

  3. 10%

  4. 21%
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For money to double in 5 years at simple interest: Interest = Principal (since 2P - P = P). So P = P×R×5/100, which gives R = 20%. At 20% simple interest, you earn the principal amount as interest in exactly 5 years, doubling your money.

Multiple choice

A certain sum of money triples itself in 8 years at simple interest. In how many years it will be eight times? / साधारण ब्याज पर 8 वर्षों में धन का एक निश्चित योग तीन गुना हो जाता है। कितने वर्षों में यह आठ गुना होगा?

  1. 16

  2. 24

  3. 27

  4. 28
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

If sum triples in 8 years, it gains 200% interest in 8 years. Simple interest rate = 200%/8 = 25% per annum. To become 8 times, sum needs 700% interest. Time required = 700%/25% = 28 years. Option D is correct. Options A, B, and C are incorrect calculations.