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 8 of 15.
Mahan Singh said:
9 years ago
Its very simple we put -x because the question is asking the difference between Interest but in compound interest formula we also put the principal value together to subtract that we will - x because x is principal value. We don't need principal value only we need interest difference.
Prasanna Kumar said:
9 years ago
SI for 2 yrs = 4% +4%.
i.e * 8%.
And CI for 2 yrs = 4+4+(4*4/100) i.e 8.16% .
Then take the options,
Given difference is ci - si = 1.
8.16% (625) - 8% (625).
ie, 51- 50 = 1.
i.e * 8%.
And CI for 2 yrs = 4+4+(4*4/100) i.e 8.16% .
Then take the options,
Given difference is ci - si = 1.
8.16% (625) - 8% (625).
ie, 51- 50 = 1.
Arun raj said:
9 years ago
CI - SI = P(r/100)square
P = principal,
R = rate = 4.
CI - SI = 1.
=>. 1 = p(4/100)square.
1= p(1/25)square,
1= p(1/625),
P = 625.
P = principal,
R = rate = 4.
CI - SI = 1.
=>. 1 = p(4/100)square.
1= p(1/25)square,
1= p(1/625),
P = 625.
Pankaj said:
9 years ago
Hi, one thing I could not understand. In question, it is given that the difference between simple and compound. Not difference between compound and simple. These two questions are distinct in the first, the answer will be in minus. So how can it possible? So please help me please.
Revant Borawat said:
9 years ago
Assume principal 100.
Then, CI=8.16 & SI=8.00,
1÷ 0.16 * 100 = 625.
Then, CI=8.16 & SI=8.00,
1÷ 0.16 * 100 = 625.
Lithin said:
9 years ago
Well said, Thank you @Muthuu.
ANUPAM DAS said:
9 years ago
We know that,
(C.I - S.I) = P * R * R/100 * 100.
HERE, 1 = P * 4 * 4/100 * 100.
P = 25 * 25 = 625.
(C.I - S.I) = P * R * R/100 * 100.
HERE, 1 = P * 4 * 4/100 * 100.
P = 25 * 25 = 625.
Krunal bhut said:
9 years ago
Interest of interest of amount is difference between SI and CI at rate given,
4% of x = 0.04x,
4% of 0.04x = (0.04x)4/100 = 1,
x = 625.
4% of x = 0.04x,
4% of 0.04x = (0.04x)4/100 = 1,
x = 625.
Fiza khan said:
9 years ago
Can anyone please explain to me how we get 51/625 x in the first answer?
SHANKAR said:
9 years ago
SIMPLE STEP.
FORMULA :
Diff b/w SI and CI when T = 2yrs.
P = (D * 100^2)/R^2.
D =RS 1.
R = 4%.
SO, Answer is 625.
FOR DIFF B/W CI AND SI FOR 3 YRS
FORMULA
P = (D * 100^3)/R^2(300 + R).
FORMULA :
Diff b/w SI and CI when T = 2yrs.
P = (D * 100^2)/R^2.
D =RS 1.
R = 4%.
SO, Answer is 625.
FOR DIFF B/W CI AND SI FOR 3 YRS
FORMULA
P = (D * 100^3)/R^2(300 + R).
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