Aptitude - Compound Interest - Discussion
Discussion Forum : Compound Interest - General Questions (Q.No. 3)
3.
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?
Answer: Option
Explanation:
Let P = Rs. 100. Then, S.I. Rs. 60 and T = 6 years.
 R = |
 |
100 x 60 |  |
= 10% p.a. |
| 100 x 6 |
Now, P = Rs. 12000. T = 3 years and R = 10% p.a.
| C.I. |
|
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|
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| = 3972. |
Discussion:
94 comments Page 1 of 10.
Subash said:
2 decades ago
Please explain the use of -1 in C.I calculation. I think here we have to subtract the principle at the back. But u use the value '1' here, I can't understand Wat u r did.
But i got the same answer by using the formula.
C.I = (Amount - Principle)
Where
Amount = {P x (1 + (R/100)^N)} - P
P = 12000.
Therefore, C.I = Rs. (12000*(1+(10/100)^3))-12000 = 3972
But i got the same answer by using the formula.
C.I = (Amount - Principle)
Where
Amount = {P x (1 + (R/100)^N)} - P
P = 12000.
Therefore, C.I = Rs. (12000*(1+(10/100)^3))-12000 = 3972
(1)
Javeed said:
2 decades ago
Dude here principle is Rs. 12000, so amount = P(1+r/100)^t
C.I = amount - principle i.e., p((1+r/100)^t )-p
Removing 'p' common factor we get:
p((1+(R/100)^T)-1)
HERE 1200 IS REMOVED AS COMMON FACTOR SINCE IT IS THE VALUE OF P.
C.I = amount - principle i.e., p((1+r/100)^t )-p
Removing 'p' common factor we get:
p((1+(R/100)^T)-1)
HERE 1200 IS REMOVED AS COMMON FACTOR SINCE IT IS THE VALUE OF P.
Priya said:
2 decades ago
Thanks Jeeva. Now I also clear abut this problem.
Anurag said:
1 decade ago
Thanks a lot. Now it became very easy.
Kusum said:
1 decade ago
Any one tel me how we got R value as 10?
Amit said:
1 decade ago
@Kusum
Simple interest formula
SI = PRN / 100
So, SI * 100 = PRN which derives new formula for R as
R = (SI * 100) / PN
Let P = Rs. 100. Then, S.I. Rs. 60 and T = 6 years.
Put all this into simple interest formula
R = (100 x 60 ) / 100 x 6 = 10% p.a.
Hope you will get it :)
Simple interest formula
SI = PRN / 100
So, SI * 100 = PRN which derives new formula for R as
R = (SI * 100) / PN
Let P = Rs. 100. Then, S.I. Rs. 60 and T = 6 years.
Put all this into simple interest formula
R = (100 x 60 ) / 100 x 6 = 10% p.a.
Hope you will get it :)
Karthi said:
1 decade ago
How we get P = Rs.100 and S.I = Rs. 60 ?
Arush said:
1 decade ago
Thanks jeeva & subash.
Vasanth said:
1 decade ago
Why we should take p value as 100?
Anmol said:
1 decade ago
@Karthi & Vasanth: you can take any value of P instead of 100.
100 is taken just for simplicity of calculation.
Now, as there is 60% rise in principal in 6 years
therefore, Net amount after 6 years, A= P+ 60% of P =1.6P
therefore interest,I= 1.6P-P= .6P
using SI formula, I= PTR/100
so, 0.6P= P*6*R/100
-> 60=6R
-> R=10%
100 is taken just for simplicity of calculation.
Now, as there is 60% rise in principal in 6 years
therefore, Net amount after 6 years, A= P+ 60% of P =1.6P
therefore interest,I= 1.6P-P= .6P
using SI formula, I= PTR/100
so, 0.6P= P*6*R/100
-> 60=6R
-> R=10%
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