Aptitude - Simple Interest - Discussion

Discussion Forum : Simple Interest - General Questions (Q.No. 12)
12.
What will be the ratio of simple interest earned by certain amount at the same rate of interest for 6 years and that for 9 years?
1 : 3
1 : 4
2 : 3
Data inadequate
None of these
Answer: Option
Explanation:

Let the principal be P and rate of interest be R%.

Required ratio =
P x R x 6
100
= 6PR = 6 = 2 : 3.
P x R x 9
100
9PR 9

Video Explanation: https://youtu.be/GaaEDwTWc6w

Discussion:
16 comments Page 2 of 2.

Manoj said:   1 decade ago
But in question it is not mentioned that principal is same.

Prasant said:   1 decade ago
Is it clear from the question that the pricipal amount is same in both the cases?

Ashik said:   1 decade ago
Assume the amount=100

If interest is 10% ,amount of interest is 10 rs.

then the amount of interest for 6 yrs = 6*10 rs = 60 rs

and for 9 yrs amt of interest for 9 years = 9*10 rs = 90rs

For ratio, s1/s2 = 60/90 = 2/3.

Anchal said:   1 decade ago
Dear Insaan and Angle, we know we got same Ans from your's method. But there is no any logic. Thats why we have to needed the interest formula. And through the interest formula we can also find out ratio even in different rate of interest.

Angle said:   1 decade ago
Lets interest of certain amount is X.

so after 6 year is 6X and after 9 year is 9X.

For Ratio ==> 6X : 9X = 2:3

Insaan said:   1 decade ago
Simple way is

S.I is directly proportional to T, we can write

S1/S2 = T1/T2
= 2/3


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