Aptitude - Simple Interest - Discussion

What is formula of simpe interest ?

S.Ib = PNR/100

S.I=PTR/100

Hi Friends!
Principle = the amt u borrowed
Interest = the small additional amt u pay for the amt u
borrowed

First let me explain u d question
In the question,
A sum of money at simple interest amounts to Rs. 815 in 3 years means the Principle amt together wit the interest paid for 3 yrs is Rs. 815 and similarly Principle amt together wit the interest paid for 4 yrs is Rs. 854

Therefore, if we subtract (854-815) we get the simple interest for 1 year as Rs. 39

Then, we calculate simple interest for 3 yrs as (39*3)= 117

Next step, we subtract (815 - 117) to get Principle amt for a yr as Rs. 698

Brief explanation for last step:

815 = Principle amt + int for 3 yrs ......equation 1
117 = int for 3 yrs ......equation 2

now subtract both equations, we get the principle amt

I hope tat this explanation will be helpful to u

Thank you gayathri. You explained well.

Simple and clear explanation by gayatri.

Superb explanation gayathri. Thanks a lot.

S.I for one yr=854-815=39
for 4 years=4*39=156
hence,854-156=698

i think it will be simple....

According to the question,

SI + P = 815 in three years and
SI + P = 854 in four years

so 815 - P = SI and
854 - P = SI
Therefore,

815 - P = (P * 3 * R)/100 and ---- eq 1
854 - P = (P * 4 * R)/100 ---- eq 2
Now,
eq 1 / eq 2 gives

(815 - P)/(854 - P) = 3/4
Solving this eq, we get
P = 698

@gayathri your explination is very helpfull.

Thank you.