Simple Interest - Solved Questions and Answers

Simple Interest is the interest calculated only on the original principal amount for a specific period of time.

Formula:

Simple Interest (SI)=\frac{P \times R \times T}{100}

Where,

• P is the Principal amount
• R is annual Rate of Interest
• T is the Time for which principal is invested

Simple Interest questions and answers are provided below for you to learn and practice.

Question 1: What would be the annual interest accrued on a deposit of Rs. 10,000 in a bank that pays a 4 % per annum rate of simple interest?

Solution : 

Here, P = 10000, R = 4, T = 1
SI = P x R x T / 100
SI = 10000 x 4 x 1 / 100
SI = 400
Thus, the annual interest would be Rs. 400

Question 2: A sum of money amounts to Rs. 28,000 in 2 years at 20 % simple interest per annum. Find the sum.

Solution : 

Here, A = 28000, T = 2, R = 20
A = P + SI
A = P + (P x R x T / 100)
A = P [1 + (R x T / 100)]
28000 = P [1 + 0.4]
P = 28000 / 1.4
P = 20000
Thus, the required sum is Rs. 20,000

Question 3: A man borrowed a certain sum of money at the rate of 6 % per annum for the first two years, 9% per annum for the next three years, and 14% per annum for the period beyond 5 years. If he pays a total interest of Rs. 22,800 at the end of 9 years, find the amount he borrowed.

Solution: 

Let the borrowed sum be P.
SI for first 2 years + SI for next 3 years + SI for next 4 years = 22800
(P x 6 x 2 / 100) + (P x 9 x 3 / 100) + (P x 14 x 4 / 100) = 22800
95 P / 100 = 22800
P = 24000
Therefore, Borrowed sum = Rs. 24,000

Question 4: At what annual rate of interest will a sum of money be thrice in 10 years?

Solution : 

Amount = Principal + SI
If the sum of money would be thrice the principal after 10 years, the SI would be twice the principal.
SI = 2 x P
(P x R x T / 100) = 2 X P
R x T / 100 = 2
R x T = 200
R x 10 = 200
R = 20 %
Thus, the required rate of interest is 20 %

Question 5: The simple interest on a sum of money in 5 years at 12 % per annum is Rs. 400 less than the simple interest accrued on the same sum in 7 years at 10 % per annum. Find the sum.

Solution: 

Let the sum be P.
SI in 5 years at 12 % per annum = P x 12 x 5 / 100 = 0.6 P
SI in 7 years at 10 % per annum = P x 10 x 7 / 100 = 0.7 P
Now, according to the question,
0.7 P – 0.6 P = 400
0.1 P = 400
P = 4000
Thus, the required sum is Rs. 4000

Question 6: A sum of Rs. 1000 was lent to two people, one at the rate of 5 % and the other at the rate of 8 %. If the simple interest after one year is Rs. 62, find the sum lent at each rate.

Solution: 

Let the sum lent at 5 % be P.
Sum lent at 8 % = 1000 – P
Now, according to the question,
SI for 5 % + SI for 8 % = 62
(P x 5 x 1 / 100) + ((1000 – P) x 8 x 1 / 100) =62
5 P + 8 (1000 – P) = 6200
P + 8000 – 8 P = 6200
3 P = 1800
P = 600
Therefore, sum lent at 5 % = P = Rs. 600
Sum lent at 8 % = 1000 – P = Rs. 400

Question 7: Calculate the simple interest on a loan of $2,000 taken for 2 years at an interest rate of 6% per year.

Solution:

SI = P × R × T/ 100​
Substituting the given values:
P = $2,000
R = 6% per year
T = 2 years
SI = 2000 × 6 × 2 / 100 = $240.

Question 8: John takes out a personal loan from his local bank for $15,000 to remodel his kitchen. The bank offers him a simple interest rate of 4.5% per year. If John plans to repay the loan in 5 years, how much will he pay in interest by the end of the loan period?

Solution:

To find the simple interest, we use the formula:
SI = P × R × T / 100​
P = $15,000
R = 4.5%
T = 5 years
SI = 15000 × 4.5 × 5 / 100
So, by the end of the 5 years, John will pay $3,375 in interest on the $15,000 loan.

Also Check:

• For Shortcuts and Tricks, you can visit Shortcuts and Tricks for Simple Interest
• For more practice problem, you can visit Problems on Simple Interest.