Aptitude - Compound Interest - Discussion

Discussion Forum : Compound Interest - General Questions (Q.No. 5)
5.
The compound interest on Rs. 30,000 at 7% per annum is Rs. 4347. The period (in years) is:
2
2 1
2
3
4
Answer: Option
Explanation:

Amount = Rs. (30000 + 4347) = Rs. 34347.

Let the time be n years.

Then, 30000 1 + 7 n = 34347
100

107 n = 34347 = 11449 = 107 2
100 30000 10000 100

n = 2 years.

Discussion:
46 comments Page 1 of 5.

Chaitu said:   1 decade ago
30000(107/100)=32100
(32100*7)/100=147 is for 1 year
2100+2100+147=4347

2 years

Lalitha said:   1 decade ago
Can any one please help how it has come (107/100)^2

Dittya said:   1 decade ago
Yaa, its because (107)^2 = 11449 and (100)^2 = 10000.

Prabakaran said:   1 decade ago
What is 107/100 ?

Anusha said:   1 decade ago
Amount=30000+4347 = 34347
amount=p(1+R/100)^n
34347=30000(1+7/100)^n
34347=30000(107/100)^n
34347/30000=(107/100)^n
11429/10000=(107/100)^n.
hence
(107/100)^2=11429/10000.

Mercy said:   1 decade ago
Simpler yet old-fashioned solution to me would be:

30000*7/100=2100 - year 1
30000+2100=32100*7/100=2247 - year 2
now add 2100+2247=4347 which was the compound interest earned after 2years.

Thus the ans is 2 years.
(1)

Swa1 said:   1 decade ago
4347=30,000(1+7/100)^n why not?
and 30,000+4347=34,347 why?
plz any one explian me.

Usha said:   1 decade ago
C.I will be the 4347.

C.I = AMOUNT-PRINCIPAL.

PRINCIPAL = 30,000.

4347 = AMOUNT-30000.

AMOUNT = 4347+30000 = 34347.

AMOUNT = P(1+R/100)^n.

34347 = 30000(1+7/100)^n.

34347/30000 = (107/100)^n.

Sumit P. said:   1 decade ago
Sorry Guys but it should;

11449 / 10000 // 34347 / 30000 is multiplied and divide by 3.

Hence, Now 11449 and 10000 are squares of 107 and 100 resp.

Thus(107 / 100)^ 2. Thus n = 2.

Anshu said:   1 decade ago
30000*7/100 = 2100 - year 1.

30000+2100 = 32100*7/100 = 2247 - year 2.

Now add 2100+2247 = 4347 which is 2 years.


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