In this Worksheet on Simple Interest, we can see the questions on calculating simple interest, rate of interest, and the amount, which is useful to the students so that they can practice for their examinations or any competitive tests. Given below are different types of questions with solutions that help you to understand the chapter better. Assess your preparation level by solving the Simple Interest Worksheet Questions on your own.

Here to solve the questions on simple interest we will use the formula,

Simple interest (S.I.) = (Principal × Rate× Time)/100 and to calculate the Amount

Amount (A) = Principal +Interest

**1.** Find the simple interest and amount in each of the following:

(a) P = $30,000 R = 10% T = 5 years

**Solution: **

Given:

Principal= $30,000

Rate= 10%

Time= 5 years.

To find Simple interest we will use the formula,

Simple interest (S.I.) = (Principal × Rate× Time)/100

= (30,000×10×5)/100

By solving we will get

Simple interest = $15,000.

(b) P= $17000 R= 20% T= 30 days

**Solution:**

Given:

Principal= $17,000

Rate= 20%

Time= 30 days

Here we will convert days to years by dividing with 365 i.e 30/365, then substitute the given values in the formula,

= (17000×20×30)/100×365

by solving we will get

Simple interest = $279.45

(c) P= $6000 R= 15% T= 13 months

**Solution:**

Given:

Principal= $6000

Rate= 15%

Time= 13 months

Here we have to convert months to years, so we will divide with 12

13÷12= 1.08 years

Simple interest (S.I.) = (Principal × Rate× Time)/100

= $975.

(d) P= $500 R= 3% T= 1 1/2 year

**Solution:**

Given:

Principal= $500

Rate= 3%

Time= 1 1/2 year= 1.5 years.

Simple interest (S.I.) = (Principal × Rate× Time)/100

= $1,350.

**2.** What sum would yield an interest of $80 in 4 years at 4% p.a.?

**Solution:**

Given:

Interest= $80

Time= 4 years

Rate= 4%

Principal = Interest×100/ Rate×Time

= 80×100/ 4×4

= $500.

3. At what rate percent per annum will $550 amount to $650 in 4 years?

**Solution:**

Given:

Amount= $650

Principal= $550

Time = 4 years

Simple interest= Amount – Principal

= $650 – $550

=$100

So Rate= Simple interest ×100 / Principal×Time

= 100×100 / 550× 4

= 4.5%

**4**. In what time will $800 amount to $1050 if the simple interest is calculated at 15% p.a.?

**Solution:**

Given:

Amount= $1050

Principal= $800

Rate = 15%

Simple interest= Amount – Principal

= $1050-$800

= $250

Time= Simple interest ×100 / Principal×Rate

= 250×100 / 800×15

= 2 1/12 years.

**5.** A sum amount to $1500 at 5% simple interest per annum after 3 years. Find the sum.

**Solution:**

Given:

Amount payable = $1500

Rate= 5%

Time= 3 years

So amount payable= Principal(100+r×t)/100

1500= Principal(100+5×3)/100

By solving we will get

Principal= $1304.34

**6.** Mr.Mike borrowed $5500 from Sam at 5% per annum. After 5 years he cleared the amount by giving $8,500 cash and a bag. Find the cost of the bag.

**Solution: **

Given:

Principal= $5,500

Rate= 5%

Time= 5 years

Simple interest (S.I.) = (Principal × Rate× Time)/100

= $1,375.

The total amount to be cleared after 5 years= Principal+Interest

= $1,375+$5,500

= $6,875

Mike cleared by paying $8,500 and a bag,

So the cost of the bag is

= $8,500-$6,875

= $1,625

**8.** In how many years will $7000 yield an interest of $4620 at 22% simple interest?

**Solution:**

Given:

Principal= $7,000

Simple interest= $4,620

Rate= 22%

Time=

$4,620= (7,000×22×Time)/100

By solving

Time= 3.04 years

**9.** At what rate of simple interest will $2800 amount to $3500 in 2 years, 3 months?

**Solution:**

Given:

Principal= $2,800

Amount= $3,500

Time= 2 years 3 months = 9/4 years

Simple interest= amount – principal

= $3,500 – $2,800

= $700

Rate= (Simple interest × 100)/ Principal× time

By substituting the values we will get rate= 11.1%

**10.** Find the simple interest at the rate of 8% p.a. for 4 years on that principal which in 6 years, 6 months at the rate of 4% p.a. gives $1600 as simple interest.

**Solution: **

Given:

Rate= 4%

Time= 6 years 6 months which is 13/2 years

Simple interest= $1600

As Principal = (Simple interest × 100)/ Rate× time

= 1600×100×2 / 13×4

= $6153.84

Now Simple interest for 4 years is

= (6153.84×4×8)/100

= $1969.22

**11. **Simple interest on a certain sum is 36/72 of the sum. Find the rate percent and time if both are numerically equal. [Hint: (T = R), P = x, S.I. = 36/72x]

**Solution:**

Let Sum be X

Time= Rate= R

Simple interest= 36/72X

Simple interest (S.I.) = (Principal × Rate× Time)/100

36/72X =(X × R × R)/100

on solving we will get 7% approx.

**12.** Simple interest on a sum of money at the end of 5 years is 2/5 of the sum itself. Find the rate percent p.a.

**Solution:**

Let Principal be X

Time= 5 years

Simple interest= 2/5X

Simple interest (S.I.) = (Principal × Rate× Time)/100

2/5X= ( X × R × 5)/100

on solving we will get

Rate= 8%