Question

The $CI$ for a sum of money for $2$ years at the rate of $10\%$ per annum compounded annually is $Rs.315$. Find the simple interest for the same sum for the same period at the same rate.

Answer 1

Compound interest $2$ years $=$Rs. $315$

Let principal$=$Rs. P

Amount $=$Principal$+$Interest

$=$Rs. $P+315$

$A=P(1+R/100{)}^n$

$P+315=P(1+10/100{)}^2$

$=P(11/100{)}^2$

$P+315=121P/100$

$100P+31500=121P$

$21P=31500$

$P=1500$

Principal is Rs. $1500$

Simple interest$=P\times R\times T/100$

$S.I=1500\times 10\times 2/100$

$S.I=30000/100$

$S.I=300$Rs.

Simple interest for $2$ years at $10\%$ on Rs. $1500$ is Rs. $300$.