Discussion
Home ‣ Aptitude ‣ Compound Interest Comments
- Question
In what time will Rs.1000 become Rs.1331 at 10% per annum compounded annually?
Options- A. 2years
- B. 3years
- C. 4years
- D. 5years
- Correct Answer
- 3years
ExplanationPrincipal = Rs.16,000;
Time=9 months = 3 quarters;
Amount
=Rs.[16000x(1+5/100)³] =[16000x21/20x21/20x21/20]
= Rs.18522.
C.I
= Rs.(18522 - 16000)
= Rs.2522.
- 4. A certain sum amounts to Rs.7350 in 2 years and to Rs.8575 in 3 years.find the sum and rate percent
Options- A. 3400
- B. 4400
- C. 5400
- D. 6400 Discuss
Correct Answer: 5400
Explanation:
Interest for 1 year is the same whether it's simple interest or the compound interest.
Now interest of third year = 8575 - 7350 = 1225; means principal for this interest is 7350 if comound interest is takenIf 7350 is the principal interest = 1225
if 100 is the principal interest =(1225/7350) * 100 = 50/3 %
When a thing increases for two successive times the overall increase on initial amount = a + b + (a * b)/100
Therefore overall interest for two years = 50/3 + 50/3 + [(50/3)*(50/3)]/100 = 325/9 %
Therefore amount after 2 years = 100 + 325/9 = 1225/9
If 1225/9 is the amount principal =100
if 7350 is the amount principal =(900/1225)*7350 =5400
So sum = 5400; Rate = 50/3 %
- 5. If the simple interest on a sum of money at 5% per annum for 3 years is Rs. 1200, find the compound interest on the same sum for the same period at the same rate.
Options- A. Rs.1251
- B. Rs.1261
- C. Rs.1271
- D. Rs,1281 Discuss
Correct Answer: Rs.1261
Explanation:
Clearly, Rate = 5% p.a .,
Time = 3 years
S.I =Rs.1200.
So,Principal
=Rs.(100 x 1200/3x5)
=Rs.8000.
Amount
=Rs.[8000 x (1+5/100)³]
=Rs(8000x21/20x21/20x21/20)
= Rs.9261
C.I
=Rs.(9261-8000)
=Rs.1261.
- 6. There is 60% increase in an amount in 6 years at simple interest. What will be the compound interest of Rs. 12,000 after 3 years at the same rate
Options- A. Rs.4972
- B. Rs.3972
- C. Rs.5972
- D. Rs.2972 Discuss
Correct Answer: Rs.3972
Explanation:
Let P = Rs. 100. Then, S.I. Rs. 60 and T = 6 years.
R= =10% p.a
Now, P = Rs. 12000. T = 3 years and R = 10% p.a.
C.I=
=Rs.3972
- 7. On a sum of money, the simple interest for 2 years is Rs. 660,while the compound interest is Rs.696.30,the rate of interest being the same in both the cases. The rate of interest is
Options- A. 10%
- B. 11%
- C. 12%
- D. 13% Discuss
Correct Answer: 11%
Explanation:
Difference in C.I and S.I for 2 years
= Rs(696.30-660)
=Rs. 36.30.
S.I for one years = Rs330.
S.I on Rs.330 for 1 year =Rs. 36.30
Rate
= (100x36.30/330x1)%
= 11%
- 8. The difference between simple interest and compound interest of a certain sum of money at 20% per annum for 2 years is Rs. 56. Then the sum is :
Options- A. Rs. 3680
- B. Rs. 2650
- C. Rs. 1400
- D. Rs. 1170 Discuss
Correct Answer: Rs. 1400
Explanation:
We know thatThe Difference between Compound Interest and Simple Interest for n years at R rate of interest is given by
Here n = 2 years, R = 20%, C.I - S.I = 56
- 9. The difference between simple and compound interests compounded annually on a certain sum of money for 2 years at 4% per annum is Rs. 1. The sum (in Rs.) is:
Options- A. 620
- B. 630
- C. 640
- D. 625 Discuss
Correct Answer: 625
- 10. The population of a town was 3600 three years back. It is 4800 right now. What will be the population three years down the line, if the rate of growth of population has been constant over the years and has been compounding annually?
Options- A. Rs.600
- B. Rs,6400
- C. Rs.6500
- D. Rs.6600 Discuss
Correct Answer: Rs,6400
Explanation:
The population grew from 3600 to 4800 in 3 years. That is a growth of 1200 on 3600 during three year span.
Therefore, the rate of growth for three years has been constant.
The rate of growth during the next three years will also be the same.
Therefore, the population will grow from 4800 by = 1600
Hence, the population three years from now will be 4800 + 1600 = 6400
Comments
There are no comments.