In this post we will solve questions of Simple Interest chapter of Quantitative Aptitude. The questions of this chapter is not that difficult but you have to spend some tie practicing its questions so that you can solve its question as quickly as possible in examination hall.
In this post you will find questions related to calculation of Simple Interest Principal and Rate of Interest which have been repeatedly asked in competition exams that’s why all the questions are important and need suitable time investment.
Simple Interest Questions
(01) A sum of money become 7/6 of itself in 3 years at a certain rate of simple interest. Find the rate of interest per annum
Principal = x,
Amount = 7x/6,
Simple Interest = 7x/6 – x = x/6
100x = 6 × x × R × 3
R =100/ (6*3) = 50/9%
Hence the rate of interest is 50/9 % per annum
(02) The simple interest on a certain sum at 5% per annum for 3 years and 4 years differ by Rs. 42. Find the principal amount
Sol:
Let the principal be x.
Rate 1 =5 %
Time 1 = 3 years
Rate 2 =5 %
Time 2 = 4 years
According to question:
The simple interest for 4 years and 3 years differ by Rs. 42
5x/100 = 42
x = 100 × 42 / 5 = Rs. 840
Hence Rs. 840 is the principal amount
(03) A sum of Rs. 10,000 is lent partly at 8% and remaining at 10% per annum. If the yearly interest on the average is 9.2%, find the two parts of the principal.
Let us divide Rs. 10000 into two parts x and 10000-x
Rs. x is lent at 8% and 10000-x is lent at 10% per annum
So,
P1 = x
R1 = 8%
T1= 1 year
P2=10000-x
R2=10%
T2= 1 year
As per the question, the yearly interest on average is 9.2%
According to question,
8x + 100000 – 10x = 92000
-2x = -8000
x = 4000
First part = Rs. 4000 and Second part = Rs. 6000
Hence the first part of principal is Rs. 4000
And second part of principal is Rs. 6000
(04) A sum of Rs. 400 amounts to Rs. 480 in 4 years. What will it amount to if the rate of interest is increased by 2%?
Principal= Rs. 400
Amount = Rs. 480
SI = Rs. (480 – 400) = Rs. 80
New Rate = 5 + 2 = 7%
New amount = Rs. ( 400 + 112 ) = Rs. 512
Hence when rate is increased by 2%, the new amount will be rs 512
Let the first part = x, then the second part = 1750 – x
P1=> x
R1=> 8%
P2 => 1750-x
R2 => 6%
As per question, the interest in first part and second part is equal
x × 8/100 × 1 = ( 1750 – x ) × 6/100 × 1
x = 750
First part = Rs. 750 and Second part = Rs. 1750 – Rs. 750 = Rs. 1000
Interest on each part = 750 × 8/100 = Rs. 60
First part = x and Second part = 5000 – x
P1= x
R1= 4%
T1 = 2 years
P2 =5000-x
R2 = 5%
T2 = 2 years
According to question:
-2x = 44000 – 50000
-2x = -6000
x = 3000
First part = 3000 and Second part = 5000 – 3000 = 2000
Required ratio = 3000 : 2000 = 3 : 2
Let the capital be Rs. x
Initial Rate of Interest
P1 =x
R1 = 8%
When rate of interest changes
P2= x
R2 =31/4%
According to question
x = 61.50 × 400 = Rs. 24,600
Hence the initial capital of money lander was Rs. 24,600
Interest From B
P1= 2500 rs
R1 = 7%
T1 = 4 years
Interest From C
P2 = Rs x
R2 = 7%
T2 = 4 Years
2500 + x = 4000
x = 4000 – 2500 = 1500
Hence, the sum lent to C is 1500 Rs
Let the sum be P.
R1 = 4%
T1 = 8 Months
R2= 5%
T2 = 15 Months
According to question
Hence Rs 3600 is the initial principal amount
Let the principal be Rs P
R1 = 11.5%
T1 = 1 year
R2= 10%
T2 = 1 year
According to question
11.5P – 10P = 5550
P = 5550 / 1.5 = Rs. 3700
Hence 3700 rs is the initial capital