Word Problems on Simple Interest | Simple Interest Problems with Solutions

Simple Interest is the interest calculated on a sum borrowed over a certain period of time. Check Simple Interest Formula and Steps on How to Calculate Simple Interest by referring to the Simple Interest Problems. Try answering the questions on simple interest available here and assess your preparation standards. Below Provided Simple Interest Word Problems makes it easy for you to understand the concept and be clear with the terms. Practice the questions on a frequent basis and make the most out of them and score better grades in exams.

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Solving Problems Involving Simple Interest

Example 1.
What sum would yield an interest of Rs 100 in 4 years at 5% per anum?

Solution:

Interest=Rs 100
Time=4 years
Annual rate=3%
principal=interest Ã—100/RateÃ—time
=100 Ã— 100/3Ã— 4
=10000/12
=833.33
Hence the principal is Rs 833.33.

Example 2.
In what time Rs 6000 amount to 8000 if the simple interest is calculated at 15% per anum?

Solution:

Amount=8000
principal=6000
Rate=15%
Simple interest=amount-principal
=8000-6000
=2000
Time=S.I Ã— 100/principal Ã— rate
=2000 Ã— 100/6000 Ã— 15
=200000/90000
=20/9=2.22=2 11/50
Hence, in 2 11/50 years, 6000 amounts to 8000.

Example 3.
A sum amount to Rs 5000 at 6% interest rate per annum after 4 years. Find the sum?

Solution:

Amount=5000
Annual rate=6%
Time=4 years
Sum=?
Amount=principal(100+rÃ—t)/100
5000=principal(100+6Ã—4)/100
5000=principal(100+24)/100
5000Ã—100/124=principal
500000/124=principal
4032.25
Hence, the principal is 4032.25

Example 4.
Simple interest on a sum of money at the end of 6 years is 3/4 of the sum itself. Find the annual rate per anum?

Solution:

Time=6
Letbprincipal is x.
SI=3/4 x.
We know that si=Principal Ã—timeÃ— Rate/100
3/4x=x Ã— 6 Ã— r/100
300/24=r
r=12.5
Hence, the Annual rate of interest is 12.5% per anum.

Example 5.
At what rate of simple interest will 12000 amount to 13000 in 3 years 3 months?

Solution:

Given principal=12000
Amount=13000
Time=2 years 3 months=9/4 years
S.I=amount-principal
=13000-12000
=1000
Rate=(simple interestÃ—100)/p Ã— t
=1000Ã—100/12000Ã—9/4
=100/12 Ã— 9/4
=900/48
=18.75
Hence, at an 18.75% annual rate, the principal 12000 will amount to 13000 in 2 years 3 months.

Example 6.
At what rate per anum will Rs 3000 amount to 3450 in 3 years?

Solution:

Amount=3450
Principal=3000
Time=3 years
S.I=amount-principal
=3450-3000
=450
R=(S.I Ã— 100)/(principalÃ— time)
=450 Ã— 100/3000 Ã— 3
=45000/9000
=45/9= 5
Hence, At 5% per anum3000 will amount to 3450 in 3 years.

Example 7.
At what rate of simple interest will the sum of money double itself in 5 years?

Solution:

Let us consider the principal as x.
t=5 years
Amount after 5 years will be doubled=2X
Simple intrest=2x-x=x.
Rate per anum=sI Ã—100/p Ã— t
=x Ã— 100/x Ã— 5
=100x/5x
=20
Therefore, at 20% the principal is doubled in 5 years.

Example 8.
Sarath invested 30000 in different bank accounts which pay 7% and 5% as annual interest. After one year he received 1450 as interest. How much did he invest in each account?

Solution:

Let x be the amount invested in the 7% bank account.
The amount invested in the 5% bank account is 30000-x.
Total interest earned in both the accounts =1450
Interest in 7% account+interest in 5% account=1450
x.7/100.1+(30000-x).5/100.1=1450
0.07x+(30000-x).0.05=1450
0.07x+1500-0.05 X=1450
0.02x=50
x=2500
30000-x=30000-2500
=27500
Therefore, Sarath invested 2500 in one account and 27500 in another account.

Example 9.
If a sum of money produces 4500 as an interest in 4 years 3 months at 15% per year simple interest, Find the principal?

Solution:

I=4500
r=15%
t=4 years 3 months
the value of ‘t’ always be in years.
So convert months into years by dividing months by 12.
Then t=4 years 3 months
=43/12 years
=41/4 years
=17/4 years
I=prt
4500=p.15/100.17/4
p=7058.823
Hence, the principal is 7058.823.

Example 10.
In how many years 8000 will double itself in 10% of the simple interest?

Solution:

Given principal=8000
r=10%
t=?
We know that SI=prt/100
=8000.10.tÃ·100
=800
simple interest is 800
So 8000+8000=16000
800 Ã· 16000=20 months=1 year 8 months
Hence,8000 will be doubled in 1 year 8 months at a 10% annual rate.

Example 11.
Simple interest on a certain sum is 15/30 of the sum. Find the rate percent and time if both are numerically equal.

Solution:

Let the sum be x.
Time=Rate=R
SI=15/30 x
We know that SI=PRT/100
15/30x=(x.R.R)/100
R2=15/30 Ã—100
=50
R=7.071
It means Time=7 years
Therefore, the annual rate is 7% and the time is 7 years.

Example 12.
Find the simple interest
p=40000,T=5 years,R=10%

Solution:

We know that Simple interest=(PÃ— R Ã—T)/100
=40000.Ã—10 Ã—5/100
=20000

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