Aptitude - Simple Interest - Discussion

Hi, I cannot understand one thing that how could be the amount increasing every year is constant?

I mean if suppose 100 is the principle and rate is 10 percent then for the first year the amount will be 110, 2nd year it will be 121, 3rd year it will be 133.10.

Now 133.1 -121 is not equal to 121-110 also not equal to 110 -100 so the increasing amount is not constant. In this problem, how can we take the increasing amount constant and directly subtract it and divide it?

I mean how is it possible that the increasing amount remains 39 over three years?

Is this the sum of money for 3 years?

Hi, guys this problem can be solved in 2 ways i.e,

Sum of 3 years ------------ 815
Sum of 4 years------------- 854
So, the difference is 1 year.
Amount 39.
So,
solution1:
39*3=117(difference*years).
815-117=698.

Sol2:
39 * 4 = 156(difference*years),
854 - 156 = 698.

Very useful discussion. Thank you all.

3years = 815.
4years = 854.
Diff = 39.
39*3 = 117.
815-117 = 698.
854-117 = 698.

Good method, Thanks @Vikram.

Hi,

Please explain me why SI calculated on 3 years why not 4 year?

S.I. for 1 year = Rs. (854 - 815) = Rs. 39.
S.I. for 3 years = Rs.(39 x 3) = Rs. 117.

Principal = Rs. (815 - 117) = Rs. 698.

Here, si=p*r*t/100.

So for 3 yrs, 815=p*r*3/100 => r=81500/3p and for 4yrs, 854=p*r*4/100 => r=85400/4p. Verify options by placing each option as p values and option which gives same values of r in both the equations is the answer. Hence, option c.

Why we find out only for three years. Is principle is found on only for the first year money?