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Aptitude questions and answers for Compound Interest
1) What is the compound interest on Rs. 2500 for 2 years at a rate of interest of 4% per annum?
- Rs. 180
- Rs. 204
- Rs. 210
- Rs. 220
The Correct answer is B
Explanation:
Principal (P) = Rs. 2500
Rate of interest(r) = 4%
Time (t) = 2 years
Compound Interest = Amount - Principal
2) What is the amount for a sum of money Rs.7500 at a 6% rate of interest C.I. for 2 years?
- Rs. 8427
- Rs. 8417
- Rs. 8400
- Rs. 8390
The Correct answer is A
Explanation:
Principal = Rs. 7500
r = 6%
t = 2 years
3) Ramesh borrowed Rs. 3600 at a certain rate of interest C.I. and the sum grows to Rs. 4624 in 2 years. What is the rate of interest?
- 12.3%
- 13.3%
- 14.3%
- 15.3%
The Correct answer is (B)
Explanation:
Principal = Rs. 3600
Amount = Rs. 4624
t = 2 years
We have;
4) On a certain sum of money the compound interest Rs. 318 is earned in 2 years. If the rate of interest is 12%, what is the principal amount?
- Rs. 1250
- Rs.1300
- Rs. 1200
- Rs. 1150
The Correct answer is A
Explanation:
We have;
C.I. = Rs. 318
r = 12%
t = 2 years
5) The simple interest on a certain sum of money at the rate of interest of 5% per annum for 2 years is Rs. 500. What is the compound interest on the same sum for the same period and at the same rate of interest?
- Rs.412.5
- Rs.400
- Rs.500
- Rs.512.5
The Correct answer is D
Explanation:
S.I. = 500
r = 5%
t = 2 years
Before finding C.I. we have to find the sum or principal;
Apply formula; Principal = 
Principal = 
= Rs. 5000
Now we have to find the Amount;
Apply formula; Amount =
Amount = 5000 
= 5000 * 1.05 * 1.05 = Rs. 5512.5
C.I. = Amount - Principal
C.I. = 5512.5 - 5000 = Rs. 512.5
6) In how many years the compound interest on Rs. 10000 at the rate of 10% will be Rs. 2100?
- 1.5 years
- 2 years
- 2.5 years
- 3 years
The Correct answer is B
Explanation:
Principal = Rs. 10000
r = 10%
C.I. = Rs. 2100
7) The difference between Simple Interest and Compound Interest on a certain sum of money for 2 years is Rs.200. If the rate of interest is 12 
- Rs. 11800
- Rs. 12000
- Rs. 12800
- Rs. 13000
The Correct answer is C
Explanation:
If the difference between the C.I. and S.I. on a certain sum of money for 2 years at a rate of interest r % is Rs. X, then the sum is given by;
Sum = X
We have;
X = Rs. 200
t = 2 years
r = 12 
Therefore, Sum = 200 
= 200 * 
= 200 * 
*
= 200 * 64
= Rs. 12800 (Option C)
8) If the difference between Simple Interest and Compound Interest on a sum of money for 3 years is Rs. 200 and the rate of interest is 10%, what is the sum?
- Rs. 6451.6
- Rs. 6351.6
- Rs. 6251.6
- Rs. 6151.6
The Correct answer is A
Explanation:
If the difference between C.I. and S.I. on a certain sum for 3 years at a rate of interest r% is Rs. X, then the sum is given by;
Sum = 
We have;
X = Rs. 200
r = 10%
Therefore, sum = 
9) The difference between simple interest and compound interest on a sum of money for 1 year at 4% per 6 months is 4, what is the sum?
- Rs. 2100
- Rs. 2300
- Rs. 2500
- Rs. 3000
The Correct answer is C
Explanation:
Let the sum = Rs. X
t = 1 year = 2 half years (6 months)
r = 4% for 6 months
10) On lending a certain sum of money on C.I. one gets Rs.9050 in 2 years and Rs.9500 in 3 years. What is the rate of interest?
- 5%
- 4.5%
- 5.5 %
- 6%
The Correct answer is A
Explanation:
Amount after 3 years = Rs. 9500
Amount after 2 years = Rs. 9050
Interest of one year= 9500 - 9050 = 450
t = 1 year
Solution 2: Quicker Method
Apply formula: Rate of interest(r): 
Y= Rs. 9500
X = 9050
