# 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 formula:

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

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

### 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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