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:
26 comments Page 3 of 3.
Lakshmanan sp said:
1 decade ago
AS p(6/5)^n>2p.
Next step (6/5)^n>2.
Next step ,take n = 1, then 6/5 = 1.2 therefore (1.2)^1 = 1.2.
|||rly for n = 2(1.2)^2 = 1.44.
For n = 3(1.2)^3 = 1.44*1.2 = 1.7288.
For n = 4(1.2)^4 = 1.7288*1.2 = 2.07.
Hence minimum no.of years is 4.
Next step (6/5)^n>2.
Next step ,take n = 1, then 6/5 = 1.2 therefore (1.2)^1 = 1.2.
|||rly for n = 2(1.2)^2 = 1.44.
For n = 3(1.2)^3 = 1.44*1.2 = 1.7288.
For n = 4(1.2)^4 = 1.7288*1.2 = 2.07.
Hence minimum no.of years is 4.
Sharvari said:
1 decade ago
Can someone explain in easier way?
Please.
Please.
Kailash said:
1 decade ago
Hello Kannan,
It got cancel (by dividing both side by P).
It got cancel (by dividing both side by P).
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 ?
Sohi said:
1 decade ago
Let x=(6/5)^n
(6/5)^n >2....................(1)
if we put value of n=1 then x=1.2.........condtion 1 is false.
if we put value of n=2 then x=1.44.........condtion 1 is still false.
if we put value of n=3 then x=1.728.........condtion 1 is false.
if we put value of n=4 then x=2.07.........now condtion 1 is true.
Hence answer is 4.
Thanx.
(6/5)^n >2....................(1)
if we put value of n=1 then x=1.2.........condtion 1 is false.
if we put value of n=2 then x=1.44.........condtion 1 is still false.
if we put value of n=3 then x=1.728.........condtion 1 is false.
if we put value of n=4 then x=2.07.........now condtion 1 is true.
Hence answer is 4.
Thanx.
Abinash said:
2 decades ago
Dear friends, Can anybody tell me in brief how it is done please?
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