 Simple Interest Practice Test available here is designed to test your knowledge of the concept. Practice the questions from the Simple Interest Practice Test and learn how to solve problems on finding the simple interest, rate, principal, amount, etc. Start answering the different questions framed on the topic and get an idea of how to approach when you come across similar kinds of problems. Step by Step Explanations provided for all the Simple Interest Questions makes it easy for you to understand the concept as well as to enhance math skills.

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Simple Interest Questions with Solutions

I. Find the Principal when S.I. = Rs 192 Rate = 6% per annum Time = 4 years?

Solution:

Given that,
S.I. = Rs 150,
Rate = 5% per annum, Time = 4 years
We know that S.I=ptr/100
150=p × 4 × 5/100
150=p × 20/100
150 × 100/20=p
p=Rs 750
Therefore, the Principal is Rs 750.

II. Find the Rate when Principal = Rs 350 Time = 2¹/₂ years S.I. = Rs 140?

Solution:

Given that,
Principal = Rs 350 Time = 2¹/₂ years S.I. = Rs 140
We know that S.I=ptr/100
140=350 × 2.5 × r/100
14000/350 × 2.5=r
r=100
Therefore, r is 100%.

III. Find the simple interest on Rs 8000 from 20 March 2020 to 7 September 2020 at 10% per annum?

Solution:

Given that,
r=10% per annum
We need to divide 10 by 365 since there are 365 days in a year.
Hence, that is 0.0274% per day
In decimal, we have to divide this percentage by 100, so, that is:
0.0274/100 = 0.000274
Daily interest on the principal is thus the multiplication of this value with the principal (8000), that is:
0.000274 * 8000 = 2.192
Now, we have to calculate the no. of days?
From 20 March till 7 September would be:
20 March – 31 March = 11 days
1 April-30 April=30 days
1May- 30 May=31 days
1 June – 30 June = 30 days
1 July – 31 July = 31 days
1 Aug – 31 Aug = 31 days
1 Sep – 7 Sep = 7 days
Total Days is 11 + 30 + 31 + 30 + 31 + 31+ 7  = 171 days
Thus, total simple interest for 171 days would be =2.192 * 171 = Rs 374.832
Hence, The simple interest is 374.832.

IV. What sum of money will earn an interest of Rs 250 in 3 years at the rate of 12% per annum?

Solution:

Given that,
S.I=Rs 250
T=3 years
R=12%
We know that S.I=ptr/100
principal=S.I * 100/t*r
=250 * 100/3*12
=25000/36=Rs 694.4
Therefore, the principal is Rs 694.4.

V. A man loses Rs 300 yearly when the yearly rate of interest tumbles from 15% to 10%. Find the capital?

Solution:

Given that,
r=15%,t=1
I=prt/100
=p× 15 × 1/100
=15p/100
r1=10%,t1=1
I1=prt/100
=p× 10 × 1/100
=10p/100
15p/100 – 10p/100 =300
p/100(15 – 10)=300
p/100 (5)=300
p=300 × 100/5
=Rs 6000
Therefore, Principal=Rs 6000.

VI. In what time will the simple interest be 3/7 of the principal at 9 percent per annum?

Solution:

Given that,
Simple interest is 3/7of the principal at 9 percent per annum.
i.e. Simple interest=3p/7
Rate = 9%
By Putting all the values in the formula SI=ptr/100,we get
3p/7=p × 9 ×time/100
time=3p × 100/7 × 9p
Time=300p/63p
Time=4.7
To convert 4.7 into months multiply it by 12.
4.7 × 12=56.35 i.e. 56 months 1 week 3 days.
Therefore in 56 months 1 week 3 days, the simple interest is 3/7 of the principal at 9 percent per annum.

VII. The simple interest on sum money is 3/5 of the principal and the number of years is equal to the rate percent per annum. Find the rate per annum?

Solution:

Let the principal be P.
The rate of interest be R%
Also given, Time=R
Simple interest =3p/5
We know that SI=ptr/100
3P/5=P × R × R/100
3P/5=PR2/100
3/5=R2/100
R2=3/5 × 100
R2=60
R=$$\sqrt{ 60 }$$
R=7.74
Therefore, the rate per annum is 7.74%.

VIII. A sum of money doubles itself in 6 years. What is the rate of interest?

Solution:

Let the sum of money that’s principal be x.
Time years
Amount after 6 years becomes double=Therefore,
Simple interest=Amount -principal=

IX. A certain sum amounts to Rs 1600 in 2 years to Rs 2200 in 4 years at simple interest. Find the sum and rate percent per annum?

Solution:

Given:
In 2 years Amount= Rs 1600…………………….(1)
In 4 years Amount =Rs 2200…………………….(2)
Let the sum =P
Rate percent = R%
From equations 1 and 2 we can say that simple interest in 2 years= 600
hence P+600=1600
p=1600-600
∴ P=Rs 1000
We know that SI=ptr/100
600=1000*R*2/100
20R=600
R=30
Therefore, the Rate of Interest is 30%.

X. Rs 10,000 were lent each to Rajesh and Rakesh at 15% per annum for 2¹/₂ years and 5 years respectively. Find the difference in the interest paid by them?

Solution:

Given that,
Rs 10,000 were lent each to Ron and Rob at 15% per annum for 3¹/₂ years and 5 years respectively.
Rajesh,
I = PRT / 100
= (10,000 × 15 × 5/2) / 100
= Rs 3750
Rakesh,
I = PRT / 100
= (10000 × 15 × 5) / 100
= Rs 7500
Difference in Interest=Rs 7500 – Rs 3750=Rs 3750
Therefore, Rakesh paid Rs 3750 more than Rajesh.

XI. In how much time will Simple interest on a certain sum of money at 12¹/₂% per annum be 3/4 for itself?

Solution:

let Principal= x
then SI = (3/4) x
We know that SI = (PRT)/100
( 3/4)x =( x × T × 25/2 ) /100
3/4x = x × T × 25/200
T=3/4 × 200/25
T = 6 years
Therefore, The time taken is 6 years.

XII. Find the time when
(a) Principal = Rs 700       Rate = 7.5% p.a       S.I. = Rs 105
(b) Principal = Rs 800       Rate = 15% p.a.       S.I. = Rs 960

Solution:

(a) Given that,
Principal = Rs 700, Rate = 7.5% p.a, S.I. = Rs 105
we know that S.I=prt/100
105=700 × 7.5 × T/100
105 × 100=700 × 7.5 × T
10500=5250 × T
T=10500/5250
= 2 years
Therefore, Time is 2 years.

(b) Given that,
Principal = Rs 800
Rate = 15% p.a.
S.I. = Rs 960
we know that S.I=prt/100
960=800 × 15 × T/100
960 × 100=800 × 15 × T
96000/12000=T
T=8 years
Therefore, Time is 8 years.

XIII. Find the simple Interest and Amount
(a) Principal = Rs 500 Rate = 10¹/₂% p.a. Time = 5 months
(b) Principal = Rs1000 Rate = 15% p.a. Time = 3 years

Solution:

Given that,
Principal = Rs 500
Rate = 10¹/₂% p.a.
Time = 5 months
We know that S.I=ptr/100
S.I= 500 × 5 × 21/2/100
S.I=500 × 5 × 21/200
S.I=Rs 262.5
Amount=Pricipal+S.I
=Rs 500 + Rs 262.5
=Rs 762.5
Therefore, S.I is Rs 262.5, Amount is Rs 762.5.
b) Given that,
Principal = Rs1000,
Rate = 15% p.a.,
Time = 3 years
We know that S.I=ptr/100
S.I=1000 × 3 × 15/100
=Rs 450
We know that Amount=Principal +Simple interest
=1000 + 450
=Rs 1450
Therefore, Simple Interest is Rs 450, Amount is Rs 1450.