1. The document contains 5 problems related to simple interest calculations. Each problem provides numerical values and asks the reader to determine an unknown variable like principal amount, interest rate, time etc. 2. Detailed step-by-step solutions are provided for each problem showing the calculations and logic to arrive at the answer. Common concepts used include simple interest formula, doubling and tripling of principal over time based on given interest rates. 3. The difficulty level of the problems ranges from 2/5 to 4/5 on a scale of 5, with the complexity of calculations and variables increasing in the later problems.

1. 1. A man lentRs.60,000, partlyat 5% and the rest at 4% simple interest.If the total annual interest
isRs. 2560, the moneylentat4% was
A) Rs. 40000
B) Rs.44000
C) Rs.30000
D) Rs. 45000
E) Rs. 46000
Ans:B
Solution:
Let the man lentthe principal amount(P) of Rs.60,000 at 4% of ‘x’ interestrate and at 5% of ‘60,000-x’
anotherinterestrate
So, letdenote itas(SI1)4%of x =
4
100
× x
And(SI2)5%of (60,000- x ) =
5
100
× (60,000-x)
So total annual interest(SI)=SI1 +SI2 ……..(1)
As SIis givenasRs. 2560
So,from equation(1)
⟹2560= (
4
100
× x) + (
5
100
× (60,000-x))
⟹2560 × 100 = 4x + 5 × 60,000 -5x
⟹X=3,00,000 – 2,56,000 = 44,000
So,X=44,000 isthe moneylentat the interestof 4%.
Sub:- Quantitative Aptitude
Chapter:- Interest
Topic:- Simple Interest
Solution by:- Shweta Tripathi
Difficulty Level:- 2/5
2. A sumof moneyat a certainrate perannumof simple interestdoublesinthe 5 yearsand a
differentrate becomesthree timesin12 years.The lowerrate of interestperannumis

2. A) 15%
B) 20%
C) 15
3
4
%
D) 16
2
3
%
E) 25%
Ans:E
Solution:
Let P=x
ThenAcco. To question,
In Case 1 – Simple interestdoublesin5years,so, at T=5years , SI=2x
As,SI=
𝑃𝑅𝑇
100
So,2 x=
𝑥𝑅5
100
here R=40%
incase 2-) 3 x=
𝑥𝑅12
100
here R=25%
so, lowerrate of interestperannumis25%
Sub:- Quantitative Aptitude
Chapter:- Interest
Topic:- Simple Interest
Solution by:- Shweta Tripathi
Difficulty Level:- 2/5
3. A persondepositedRs.400 for 2 years,Rs. 550 for4 yearsand Rs. 1,200 for 6 years.He received
the total simple interestof Rs.1,020. The rate of interestperanuumis
A) 10%
B) 5%
C) 15%
D) 20%

3. E) 25%
Ans:A
Solution:
P1=Rs.400 , P2=Rs. 550 , P3=Rs.1200
T1=2 years , T2=4 yeas , T3=6 years
Let the rate of interestdenotedbyR,as
Simple Interest(SI) =(P1RT1)/100 + (P2RT2)/100 + (P3RT3)/100
⟹ 1020 = (400×R×2)/100 + (550×R×4)/100 + (1200×R×6)/100
⟹1020 = 102R
⟹ R = 10
Hence rate of interestperannumis10%.
Sub:- Quantitative Aptitude
Chapter:- Interest
Topic:- Simple Interest
Solution by:- Shweta Tripathi
Difficulty Level:- 2/5
4. The simple interestonasum of moneyis
1
16
of the principal andthe numberof yearsis equal to
the rate percent perannum, thenrate per centperannum is
A) 1
1
2
%
B) 2
1
2
%
C) 3
1
2
%
D) 4
1
2
%
E) 5
1
2
%
Ans:B
Solution:LetP=x

4. Acco. to question,
SI=(1/16) of x and alsorate if interestisequai totime meansR=T
So,SI=
𝑃𝑅𝑇
100
(1/16)x =
𝑥×𝑅×𝑅
100
(PuttingRon place of T )
R2
= (100/16)
⟹R=(5/4)
⟹R=2
1
2
%
Sub:- Quantitative Aptitude
Chapter:- Interest
Topic:- Simple Interest
Solution by:- Shweta Tripathi
Difficulty Level:- 3/5
5. A sum of moneyat some rate of simple interestamountstoRs.2,900 in8 yearsand to Rs.3,000
in10 years.The rate of interestperannumis
A) 4%
B) 2
1
2
%
C) 3%
D) 2%
E) 1%
Ans:D
Solution:
Rs. 2900 in8 yearsand Rs. 3000 in10 years
SI forfirstyear =
(3000−2900)
(10−8)
=
100
2
= 50
SI for10 years= 50 ×10 = Rs.500
Principal Amount(P) =3000 – 500 = Rs.2500

5. So, rate of interestperannum,
50 =
2500×𝑅×1
100
⟹R = 2%
Sub:- Quantitative Aptitude
Chapter:- Interest
Topic:- Simple Interest
Solution by:- Shweta Tripathi
Difficulty Level:- 4/5