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.
Fiza khan said:
9 years ago
Can anyone please explain to me how we get 51/625 x in the first answer?
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.
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.
Lithin said:
9 years ago
Well said, Thank you @Muthuu.
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.
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.
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.
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.
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.
MALINIMADHAVAN said:
9 years ago
S.I = PNR/100.
=(PX2X4)/100,
=(PX2X1)/25.
THEREFORE S.I = PX2/25 = 0.008P,
C.I = P(1+R/100)^N -P,
= P(1+4/100)^2 -P,
=P(1+1/25)^2 - P,
= P(25+1/25)^2 -P,
= P(26/25)^2-P,
= P(1.04)^2-P,
= P(1.0816)-P,
=1.0816P-P.
C.I =.0816P.
DIFFERENCE:
CI-SI = 1
0.0816P - 0.08P =1,
0.0016P = 1,
P = 1/0.0016 = 625.
THEREFORE, SUM IN RUPEES IS 625Rs.
=(PX2X4)/100,
=(PX2X1)/25.
THEREFORE S.I = PX2/25 = 0.008P,
C.I = P(1+R/100)^N -P,
= P(1+4/100)^2 -P,
=P(1+1/25)^2 - P,
= P(25+1/25)^2 -P,
= P(26/25)^2-P,
= P(1.04)^2-P,
= P(1.0816)-P,
=1.0816P-P.
C.I =.0816P.
DIFFERENCE:
CI-SI = 1
0.0816P - 0.08P =1,
0.0016P = 1,
P = 1/0.0016 = 625.
THEREFORE, SUM IN RUPEES IS 625Rs.
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