Finding the Principal Amount | Simple Interest | Aptitude | IndiaBIX

A sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 854 in 4 years. The sum is:

[avinavayushman]

The explanation might be in this way,
Suppose the time period be 2010. Now exactly in the year 2013 the SI is Rs. 815 and exactly in the year 2014 it's Rs. 854. Since the given year is consecutive so subtracting them would the SI for one year (like from 2010 to 2011 to 2011 to 2012), i.e. Rs.39. Then for through 3 years, it would 3*39=117 or for through 4 years, it would 4*39.=156. And using the formula
"Amount = SI+Principle"
when we subtract 815-117 or even 854-156 would give the Rs.698, which the required sum or basically our Principle amount which we invested.

[anishvaddadi]

Hello sir,
We want explanation .
You simply derive the solution,
Without any explanation

[kiransolanki]

117 interest is on 815 principle....but 815 is amount for the initial sum...so you can't calculate interest on amount.

[shivamtiwari]

i want to know that for calculating one year Simple interest why you did 854-815? what"s the logic in it? and Also for finding out principal why u did 815-117?

[pondarajagadeesh]

what is this ?you just did writing the numbers and wrote answer!!what is the use sir, we want the clear explanation.