Simple Interest Aptitude Questions and Answers – Quantitative Aptitude

Simple Interest Aptitude Questions and Answers – Formulas & Tricks

Principal: The Money borrowed or lent out for a certain period is called Principal or the Sum.

Interest: Extra money paid for using other’s money is called interest.

Simple Interest: If the interest on a sum borrowed is reckoned uniformly, then it is called Simple Interest.

  • Simple Interest (SI)= (P * R * T) / 100
  • Principal (P) = (100 * SI) / (R * T)
  • Rate (R) = (100 * SI) / (P * T)
  • Time (T) = (100 * SI) / (P * R)
  • Amount (A) = P + SI => P + (P * R * T) / 100
  • If a certain sum of money becomes n times itself at R% p.a simple interest, then the time T’ in which it will become m times itself is given by T’ = (m – 1 / n – 1) * T years
  • If a certain sum of money P lent out at SI amounts to A1 in T1 Years to A2 in T2 Years, then
    • P = (A1T2 – A2T1) / (T2 – T1)
    • R = (A1 – A2) / (A1T2 – A2T1) * 100%
  • If a certain sum of money P lent out for a certain time T amounts to A1 at R1 % Per annum and to A2 at R2 % Per annum, then
    • P = (A2R1 – A1R2) / (R1 – R2),
    • T = (A1 – A2) / (A2R1 – A1R2) * 100 years

Simple Interest Aptitude Questions and Answers With Detailed Explanation – Quantitative Aptitude

Simple Interest

Question 1
How much Simple Interest can a person get on Rs. 8,200 at 17.5% p.a. for a period of 2 years and 6 months?
A
Rs. 2,850
B
Rs. 3,587.50
C
Rs. 3,750
D
Rs. 3,770.50
Question 1 Explanation: 
Answer: Option B
Explanation:
SI = (8200 * 2.5 * 17.5)/100
=(8200 * 5 * 35)/(100 * 2 * 2)
SI = Rs. 3587.50
Question 2
A sum fetched a total simple interest of Rs. 4016.25 at the rate of 9 p.c.p.a in 5 Years. What is the sum?
A
Rs. 8, 725
B
Rs. 8, 825
C
Rs. 8, 875
D
Rs. 8, 925
Question 2 Explanation: 
Answer: Option D
Explanation:
Principal = Rs. (100 * 4016.25)/ (9 * 5)
=Rs. 401625 / 45
Principal = Rs. 8, 925
Question 3
In 30 years an amount becomes 5 times the original amount. What is the rate of interest?
A
6.67%
B
12.5%
C
13.33%
D
24%
Question 3 Explanation: 
Answer: Option C
Explanation:
Original Amount = p
In T= 30 years, Amount = 5p
Therefore, Interest received in 30 years = 5p - p = 4p
Simple Interest = (PRT / 100)
4p = (p * r * 30) / 100
Therefore, R = 13.33%
Question 4
If Rs. 460 amount to Rs. 640 in 6 years, What will it amount to in 2 years at the same rate %?
A
Rs. 520
B
Rs. 585
C
Rs. 700
D
Rs. 640
Question 4 Explanation: 
Answer: Option A
Explanation:
Interest for 6 years = 640 - 460 = Rs. 180
Interest for 2 years =(180/6) * 2 = Rs. 60
Therefore, 460 will become 460 + 60 = Rs. 520 after 2 years.
Question 5
The simple interest on a sum of money is of the principal and the number of years is equal to the rate % p.a. The rate % p.a. is
A
5%
B
6%
C
10%
D
9%
Question 5 Explanation: 
Answer: Option A
Explanation:
P/4 = (P * R * R)/100 -> R2 = 25% -> R = 5%
Question 6
How much time will it take for an amount of Rs. 450 to yield Rs. 81 as interest at 4.5% per annum of Simple Interest?
A
3.5 years
B
4 years
C
4.5 years
D
5 years
Question 6 Explanation: 
Answer: Option B
Explanation:
Time = (100 * 81) / (450 * 4.5) Years = 4 years
Question 7
What will be the ratio of Simple Interest earned by certain amount at the same rate of interest for 6 years and that for 9 years?
A
1 : 3
B
1 : 4
C
2 : 3
D
2 : 5
Question 7 Explanation: 
Answer: Option C
Explanation:
Let the principal be p and rate of interest be R%
Therefore, Required Ratio =
= (6PR) / (9PR) = 6 / 9
Required Ratio = 2 : 3
Question 8
Abha took a loan of Rs. 1200 with simple interest for a many years as the rate of interest. If she paid Rs. 432 as interest at the end of the loan period, What was the rate of interest?
A
3%
B
6%
C
9%
D
12%
Question 8 Explanation: 
Answer: Option B
Explanation:
Let rate = R% and time = R years
Then, (1200 * R *R)/100 = 432
=> 12R^2 = 432
=>R^2 = 36
R = 6
Question 9
A sum was put at simple interest at a certain rate for 10 years. Had it been put at 5% higher rate, it would have fetched Rs. 600 more. What was the Sum?
A
Rs. 1200
B
Rs. 1300
C
Rs. 1400
D
Rs. 1500
Question 9 Explanation: 
Answer: Option A
Explanation:
At 5% more rate, the increase in SI for 10 years = Rs. 600(given)
So, at 5% more rate, the increase in SI for year = 600/10 = Rs. 60/-
That is, Rs.60 is 5% of the invested sum
So, 1% of the invested sum = 60/5
Therefore, the invested sum = 60 * (100/5) = Rs. 1200
Question 10
The simple interest on Rs. 25 for 4 months at the rate of 3 paisa per rupee per month is:
A
240 paise
B
Rs. 1.40
C
Rs. 2.20
D
Rs. 3
Question 10 Explanation: 
Answer: Option D
Explanation:
I = (PTR) / 100
I = (25 * 4 * 0.03) / 100
I = 0.03 * 100 = 300ps
I = Rs. 3
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