Aptitude - Compound Interest - Discussion
Discussion Forum : Compound Interest - General Questions (Q.No. 2)
2.
The difference between simple and compound interests compounded annually on a certain sum of money for 2 years at 4% per annum is Re. 1. The sum (in Rs.) is:
Answer: Option
Explanation:
Let the sum be Rs. x. Then,
| C.I. = |  |
x |  |
1 + | 4 |  |
2 | - x |  |
= | |
676 | x | - x | |
= | 51 | x. |
| 100 | 625 | 625 |
| S.I. = | |
x x 4 x 2 | |
= | 2x | . |
| 100 | 25 |
 |
51x | - | 2x | = 1 |
| 625 | 25 |
x = 625.
Discussion:
149 comments Page 2 of 15.
Sudharsan said:
1 decade ago
For beginners those are asking why they used -x in step one.
Let me explain you clearly.
First take Amount=Rs.5000 and Rate=2% Years=1
Then calculate SI, SI=PNR/100
So, SI=5000*1*2/100=RS100
[Here you are getting only interest]
Now calculate CI, CI=P(1+r)^n
So, CI=5000*(1+2/100)^1=RS5100
[Here we are getting interest+Principal amount]
That's why there are using -x in the formula.
If you use -x(for our example its P) we will get the interest only.
Let me explain you clearly.
First take Amount=Rs.5000 and Rate=2% Years=1
Then calculate SI, SI=PNR/100
So, SI=5000*1*2/100=RS100
[Here you are getting only interest]
Now calculate CI, CI=P(1+r)^n
So, CI=5000*(1+2/100)^1=RS5100
[Here we are getting interest+Principal amount]
That's why there are using -x in the formula.
If you use -x(for our example its P) we will get the interest only.
Vishal kumar said:
1 decade ago
Shortcut method
Difference = (D*R^2)/100^2 for 2 year
Difference = {(D*R^2)(300+R)}/100^3 for 3 year.
Difference = (D*R^2)/100^2 for 2 year
Difference = {(D*R^2)(300+R)}/100^3 for 3 year.
Siva said:
1 decade ago
@sudharshan.
Rightly said, cleared because of you.
Rightly said, cleared because of you.
Atanu said:
1 decade ago
Shortcut Method
sum = difference*(100/R)^2 for 2 year
sum = {difference*(100^3)}/{R^2*(300+R)} for 3 year
sum = difference*(100/R)^2 for 2 year
sum = {difference*(100^3)}/{R^2*(300+R)} for 3 year
RAJEEV said:
1 decade ago
A=P( 1+R/100)
C.I=A-P
DIFFERENCE OF CI AND S.I FOR X YEAR= P*(R/100)^X
C.I=A-P
DIFFERENCE OF CI AND S.I FOR X YEAR= P*(R/100)^X
SAILAJA said:
1 decade ago
CI-SI=1,
T=2
R=4
P=?
SHORTCUT IS
CI-SI=P(R/1OO)^2
1=P(4/100)^2
P=625
T=2
R=4
P=?
SHORTCUT IS
CI-SI=P(R/1OO)^2
1=P(4/100)^2
P=625
Priya said:
1 decade ago
C.I-S.I=P(R/100)^2
IS THIS FORMULA CORRECT?
IS THIS FORMULA CORRECT?
Siri said:
1 decade ago
Shortcut method: difference= sum (rate/100) ^2.
AKSHAY said:
1 decade ago
The correct formula is (ci-si) (100/r) (100/r) = p.
NOTE: (THIS FORMULA IS FOR TWO YEARS ONLY).
NOTE: (THIS FORMULA IS FOR TWO YEARS ONLY).
Pankaj parashar said:
1 decade ago
Short cut method:
si rate for 2 years=8%
ci rate for 2 years=8.16%
diff=.16% ie is equal to re 1
so 1/.16*100=625
si rate for 2 years=8%
ci rate for 2 years=8.16%
diff=.16% ie is equal to re 1
so 1/.16*100=625
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