Simple Interest Questions and Answers

Simple Interest Questions and Answers

On this page we are going to discuss Simple Interest Questions and Answers, with basic definition and practice examples.
Simple Interest Questions and Answers

Simple Interest formula:

Suppose, principle = P, rate of interest(%) = R, total time = T.

Hence, Simple Interest = \frac{P\times R\times T}{100}

Formula of Simple Interest Problems

Practice Questions on Simple Interest

Example 1:

The Interest received at 15% per annum simple interest after 3 yrs is Rs. 630. What was the principal (in Rs)?

Options:

a. Rs. 1200
b. Rs. 1750
c. Rs. 1400
d. Rs. 2000

Explanation:

I = \frac{P\times R\times T}{100}
630 = \frac{P\times 15\times 3}{100}

P = Rs. 1,400

Hence, Option C is correct.

Example 2:

A sum of money becomes 9 times in 20 years. Find the 10 times of rate of interest.

Options:

a. 350%
b.
45%
c. 400%
d. 250%

Explanation:

According to the formula,

\text{ Rate } = \frac{100(n – 1)}{T}

= \frac{100(9 – 1)}{20} = \frac{800}{20} = 40%

∴ 10 times of 40% = 400%

Hence, option C is correct.

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Practice Simple Interest Questions with Answers

1. If the amount is Rs. 625. Calculate its simple interest at 13/2% per annum for two and a half years.

110.65

110.65

11.66%

105.85

105.85

8.75%

101.56

101.56

65.6%

None of the above

None of the above

13.99%

Simple Interest = (Principal * Rate * Time) / 100

In this case, the principal amount is Rs. 625, the rate is 13/2% (which can be written as 13/2/100), and the time is 2 and a half years.

Let's substitute the given values into the formula:

Simple Interest = (625 * (13/2) * (5/2)) / 100

Simplifying further:

Simple Interest = (625 * 13 * 5) / (2 * 2 * 100)

Simple Interest = (40625) / (400)

Simple Interest = 101.5625

Therefore, the simple interest for the amount of Rs. 625 at a rate of 13/2% per annum for two and a half years is Rs. 101.56.

2. Calculate the simple interest at 9% annually for the period from 21st august 1993 to 21st august 1994 on the amount of Rs. 800.

75

75

4.73%

74.5

74.5

6.8%

72

72

85.5%

70.5

70.5

2.96%

Given, principal = 800

Rate = 9%
Time = 1 year

Simple interest = p * r * t/100

= 800 * 9 * 1 / 100 = 72

3. The simple interest for the period of 3 years at 19/2 % annually amounts to Rs. 159.60. Find the principal amount.

580

580

5.7%

590

590

8.39%

650

650

7.38%

560

560

78.52%

 P = 100 * S.I / R * T

= 100 * 159.60/ 3 * 9.5 = 560

4. Find in how many years a person will get 87 as simple interest at 4% p.a. on Rs. 725.

2.5

2.5

8.07%

3

3

81.75%

4.25

4.25

7.02%

9.6

9.6

3.16%

T = 100 * S.I./ P * R

= 100 * 87 / 725 * 4

= 8700/2900 = 3 years

5. 9/16 of the amount is its simple interest. Calculate the annual rate and period, if both are equal.

15/2 and 15/2

15/2 and 15/2

68.53%

15/2 and 17/2a

15/2 and 17/2a

9.56%

17/2 and 19/2

17/2 and 19/2

7.17%

None of the above

None of the above

14.74%

Let the amount be Re. 1, then simple interest = 9/16 * 1

Let us assume the rate as x%, and time as x

Then, 1 * x * x /100 = 9/16

x2/100 = 9/16

16 x2 = 900

x2 = 900/16

x = 30/4 or 15/2

6. A certain amount was kept to acquire simple interest for 2 years at some rate. Had it put at a higher rate of 3%, it would have made Rs. 72 more. Calculate the sum.

1230

1230

6.06%

1200

1200

82.32%

1275

1275

7.58%

1369

1369

4.04%

Let us assume the sum as 100 and rate as r

Then, simple interest = 100 * r * 2/100 = 2r

Simple interest on r + 3 = 100 * (r+3) * 2 / 100 = 2r + 6

Difference between two simple interest = 2r + 6 – 2r = 6

Therefore, if the difference is 6 than the sum is 100

If difference is 72, then sum = 100 * 72/6 = 1200

7. A certain sum of money is changed to 678 in 2 years and 736.50 in 3.5 years. Calculate the sum of money and the rate of interest.

550 and 5.5%

550 and 5.5%

9.95%

650 and 4.5%

650 and 4.5%

15.18%

600 and 6.5%

600 and 6.5%

67.02%

None of the above

None of the above

7.85%

Principal amount + interest of three and half years = 736.50

Principal amount + interest of two years = 678

By subtracting we get, 58.50, interest for one and half year.

Therefore, interest for 2 years = 58.50 * 2 * 2/ 3 = 78

Therefore, principal amount = 678 – 78 = 600

Hence, rate = 100 * 78/600 * 2 = 6.5%

8. Calculate the rate per annum, if the money doubles in 10 years.

5.6%

5.6%

8.17%

22/5%

22/5%

6.25%

33/2%

33/2%

2.88%

10%

10%

82.69%

Let us assume the principal amount as p and rate as r. Since the amount doubles in 10 years, therefore simple interest is p

Therefore, p = p * r * 10/100

= 10r = 100

r = 100/10 = 10%

9. If Rs. 5600 amount to Rs. 6678 in 3.5 years. What will Rs. 9400 amount to in 21/4 years at a similar rate per annum?

12114.25

12114.25

69.41%

13225.65

13225.65

11.76%

14289.65

14289.65

11.76%

12555.55

12555.55

7.06%

Rate = 100 * S.I. /p*t

= 100 * 1078/ 5600 * 3.5 = 5.5%

Therefore, simple interest on 9400 = (9400 * 21/4 * 5.5)/100 = 2714.25

Hence, amount = 12114.25

10. A sum of money is changed to Rs 767 in 3 years and 806 in 4 years. Calculate the sum.

600

600

7.69%

650

650

81.03%

700

700

5.64%

675

675

5.64%

Simple interest for 1 year = simple interest for 4 years – simple interest for 3 years

806 – 767 = 39

Simple interest for 3 years = 39 * 3 = 117

Therefore, sum = 767 – 117 = 650

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