Question

The compound interest on a certain sum for $2$ years is Rs. $786$ and S.I. is Rs. $750$. If the sum is invested such that the S.I. is Rs. $1296$ and the number of years is equal to the rate per cent per annum, Find the rate of interest.

Answer 1

Compound interest for 2 years = Rs. 786

Simple interest for 2 years = Rs. 750

Interest for 2 years = I = $\frac{CI-SI}{n}\times 100=\frac{786-750}{360}\times 100$

$=\frac{36}{36}\times 10=10$%

P for first year Rs. 3600. Let the time and rate = x

$I=PRT\Rightarrow 1296=3600\times x\times x\Rightarrow x^2=0.36\therefore x=0.6$