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

Sasidharan took a loan of Rs. 20,000 to purchase a colour TV set from Royal Finance Co. He promised to make the payment after three years. The company charges compound interest @ 10% p.a. for the same. But, suddenly the company announces the rate of interest as 15% p.a. for the last one year of the loan period. What extra amount Sasidharan has to pay due to his announcement of now rate of interest?

  1. Rs. 7,830

  2. Rs. 6,620

  3. Rs. 4,410

  4. Rs. 1210

  5. Rs. 3,000
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Original interest: 20000 * (1.1)^3 = 26620. New interest: 20000 * (1.1)^2 * 1.15 = 20000 * 1.21 * 1.15 = 27830. Difference = 27830 - 26620 = 1210.

Multiple choice

Deepak invested Rs. 76000 at simple interest for 2 years at the rate of R% and gets an interest of Rs. 20520. If he invested total amount (Principle + Interest) in another scheme, which offered compound interest at the rate of (R%+1.5%) then find total compound interest obtained by Deepak after 2 years?

  1. a) Rs. 32117.2

  2. b) Rs. 37121.3

  3. c) Rs. 31127.7

  4. d) Rs. 37177.2

  5. e) Rs. 34217.7
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Simple interest = P*R*T/100. 20520 = 76000 * R * 2 / 100 => 20520 = 1520 * R => R = 13.5%. New rate = 13.5 + 1.5 = 15%. Total amount = 76000 + 20520 = 96520. Compound interest = 96520 * ((1.15)^2 - 1) = 96520 * 0.3225 = 31127.7.

Multiple choice

Veer invested 1/3 rd of his total investment at 5% and 1/5 th at 4% and rest of money at 3% per annum simple interest for the one year and received total interest of Rs 290. find the total sum invested by Veer?

  1. (a) Rs.15000

  2. (b) Rs.7500

  3. (c) Rs.10000

  4. (d) Rs.12000

  5. (e) Rs.18000
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let total sum be S. Interest = (S/3 * 0.05) + (S/5 * 0.04) + (7S/15 * 0.03) = 290. (S/15 * 0.25) + (S/15 * 0.12) + (S/15 * 0.21) = 290. (0.58 * S) / 15 = 290. S = (290 * 15) / 0.58 = 4350 / 0.58 = 7500.

Multiple choice

Directions: Each question is followed by three statements. You have to study the question and all the three statements given and decide whether any information provided in the statement(s) is redundant and can be dispensed with while answering the questions. What is the compound interest on a sum? A. An amount becomes Rs. 4410 at the compound rate of 5% in 18 months. B. An amount becomes Rs. 5324 in 3 years. C. Compound rate of interest is 10%

  1. Either A alone or B and C together

  2. B and C together

  3. Either B or C

  4. Only C

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

To find compound interest, we need the principal, rate, and time. Statement C gives the rate. A gives amount, rate, and time, allowing us to find the principal. B gives amount and time, but without the rate, we cannot find the principal. Thus, A alone or B+C together are sufficient.

Multiple choice

Harvir invested Rs. x at simple interest for 3 years at the rate of R% per annum and got an interest of Rs. 4,410. If Rs. x are invested at compound interest for 3 years at the rate of 10% per annum then the interest will be Rs. 6,951. What is the value of R? (I) 6 > R > 5 (ii) 7 > R > 5 (iii) 8 > R > 6 (iv) 9 > R > 7 (v) 10 > R > 9

  1. Only (i)

  2. Only (ii)

  3. Only (iii)

  4. Only (iv)

  5. only (v)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Simple interest: 4410 = x * R * 3 / 100, so xR = 147000. Compound interest: 6951 = x * ((1.1)^3 - 1) = x * 0.331. x = 6951 / 0.331 = 21000. R = 147000 / 21000 = 7. The range 8 > R > 6 includes 7.

Multiple choice

The simple and compound interest obtained at the rate of x% and y% on a sum of Rs. 15,000 is Rs. 2700 and Rs. 4965, respectively. If the time period for simple interest was 2 years and for compound interest was 3 years, then which of the following is correct, given that the interest was calculated yearly? (i) xy = 90 (ii) x + y = 19 (iii) x – y = 1 (iv) y – x = -1 (v) x2 + y = 91

  1. Only (i) and (ii)

  2. Only (i), (ii) and (v)

  3. Only (ii), (iii) and (v)

  4. Only (iii) and (iv)

  5. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For simple interest, 15000 * x * 2 / 100 = 2700, so x = 9. For compound interest, 15000 * (1 + y/100)^3 - 15000 = 4965. Solving (1 + y/100)^3 = 1.331 gives 1 + y/100 = 1.1, so y = 10. Checking the options: (i) xy = 90 (True), (ii) x + y = 19 (True), (v) x^2 + y = 81 + 10 = 91 (True).

Multiple choice

A and B invested Rs. 24,000 each. A invested at simple interest at the rate of 9% per annum and B invested at compound interest at the rate of x% per annum. If both A and B invested the money for two years, what could be the possible value of x given that B got at least Rs. 3420 more interest than A? (i) 15% (ii) 14% (iii) 18% (iv) 12% (v) 10%

  1. Only (ii), (iv) and (v)

  2. Only (ii) and (iv)

  3. Only (i) and (iii)

  4. Only (i), (iii) and (v)

  5. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A's interest = 24000 * 0.09 * 2 = 4320. B's interest = 24000 * ((1 + x/100)^2 - 1). We need B - A >= 3420, so B >= 7740. (1 + x/100)^2 - 1 >= 7740 / 24000 = 0.3225. (1 + x/100)^2 >= 1.3225. 1 + x/100 >= 1.15. x >= 15. Options (i) 15% and (iii) 18% satisfy this.

Multiple choice

Jerman invested Rs. 27,000 at the rate of 13% simple interest per annum in a bank for two years. At how much more rate of compound interest per annum he would have yielded at least Rs. 4860 more on same amount in same number of years? (i) 3% (ii) 5% (iii) 7% (iv) 9% (v) 20%

  1. Only (iii), (iv) and (v)

  2. Only (i) and (ii)

  3. Only (iv) and (v)

  4. Only (v)

  5. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Simple Interest = 27000 * 0.13 * 2 = 7020. Compound Interest = 27000 * ((1+r)^2 - 1). We want CI - 7020 >= 4860, so CI >= 11880. (1+r)^2 - 1 >= 11880/27000 = 0.44. (1+r)^2 >= 1.44. 1+r >= 1.2, so r >= 0.2 or 20%.

Multiple choice

A person invested Rs. 32,000 at simple interest and Rs. 30,000 at compound interest for 2 years at the rate of 6% and 12% per annum, respectively. Because of some error, simple interest got calculated at 9% and compound interest got calculated at 24%. What amount of interest is to be deducted so that the person gets the correct amount of money after 2 years?

  1. Rs. 10,516

  2. Rs. 10,416

  3. Rs. 10,316

  4. Rs. 10,116

  5. Rs. 9,416
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Calculate the interest at the intended rates and the interest at the error rates. The difference is the amount to be deducted.

Multiple choice

Interest earn on a sum of money at some rate of compound interest for 2 years equal to the interest earn when same sum of money invested at 7% interest in another scheme with S.I. for 3 years. If Interest earn in C.I. for 3 years on same sum of money is Rs. 1655, then find out the initial sum of money.

  1. 4500

  2. 5400

  3. 5000

  4. 6000

  5. 5500
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let P be the principal. CI for 2 years at r% = P((1+r/100)^2 - 1). SI for 3 years at 7% = P * 3 * 0.07 = 0.21P. Equating: (1+r/100)^2 - 1 = 0.21. (1+r/100)^2 = 1.21. 1+r/100 = 1.1, so r = 10%. Now, CI for 3 years at 10% = P((1.1)^3 - 1) = P(0.331) = 1655. P = 1655 / 0.331 = 5000.

Multiple choice

Shivam and Amit invest equal sum. Shivam invested on C.I. for two years at the rate of 15% p.a. and Amit invested 3/4th of sum at some rate of simple interest and remaining sum at the rate of 9% p.a. on simple interest. If interest received by both at the end of two years are equal, then find the interest earned by Amit?

  1. 8000

  2. 9000

  3. 10000

  4. can't be determined

  5. e) 12000 12000
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Shivam's two-year compound interest is 32.25% of the invested sum. Amit's interest is equal to this amount, but the rate on the first three-fourths of his investment is unspecified. Since the common principal is also not given, the numerical interest cannot be determined.