Aptitude - Compound Interest - Discussion
Discussion Forum : Compound Interest - General Questions (Q.No. 8)
8.
The least number of complete years in which a sum of money put out at 20% compound interest will be more than doubled is:
Answer: Option
Explanation:
| P |  |
1 + | 20 |  |
n | > 2P |  |
|
6 | |
n | > 2. |
| 100 | 5 |
| Now, | |
6 | x | 6 | x | 6 | x | 6 | |
> 2. |
| 5 | 5 | 5 | 5 |
So, n = 4 years.
Discussion:
28 comments Page 2 of 3.
Sayan Duary said:
2 weeks ago
Shortcut :
We need:
(1.2)^n > 2.
Check powers:
1.2^3 = 1.728 < 1.2^4 = 2.0736>2.
So, the least number of complete years is 4 years
We need:
(1.2)^n > 2.
Check powers:
1.2^3 = 1.728 < 1.2^4 = 2.0736>2.
So, the least number of complete years is 4 years
ABHI said:
10 months ago
@All.
Here's my explanation.
Time to double(in years) ≈ 72/ Rate.
T = 72/20 = 3.6.
Closest whole number is 4.
Therefore, T = 4 years.
Here's my explanation.
Time to double(in years) ≈ 72/ Rate.
T = 72/20 = 3.6.
Closest whole number is 4.
Therefore, T = 4 years.
(3)
Jahnavi said:
1 decade ago
Guys can you pls explain what is the first formula we are using there:
i.e., p(1 + 20/100)^n > 2p.
what is actually?
i.e., p(1 + 20/100)^n > 2p.
what is actually?
Ashok said:
1 decade ago
@Kalyani.
In question, they asked how much of year will give the principal amount doubled so the only 2p is used.
In question, they asked how much of year will give the principal amount doubled so the only 2p is used.
Tanish said:
5 years ago
@All.
When you divide 72 by ROI you will get an approximate no of years in which the principal will get double.
When you divide 72 by ROI you will get an approximate no of years in which the principal will get double.
(6)
Kannan said:
1 decade ago
Hi friends,
In the explanation, in 1st step p is present.
But in 2nd step it is vanished where it is gone ?
In the explanation, in 1st step p is present.
But in 2nd step it is vanished where it is gone ?
Dilip said:
1 decade ago
@Kalyani
Suppose double principle then 2p.
Triple principle then 3p.
I hope you can understand.
Suppose double principle then 2p.
Triple principle then 3p.
I hope you can understand.
(1)
Anjali said:
1 decade ago
I am unable to understand why are taking amount formula in place of CI. Please explain it.
Dhairya adhikari said:
1 decade ago
Easy method:
n = 72/r,
n = 72/20 = 3.6 years,
n = 4 years approximately.
n = 72/r,
n = 72/20 = 3.6 years,
n = 4 years approximately.
Abinash said:
2 decades ago
Dear friends, Can anybody tell me in brief how it is done please?
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