Answer: Option B
Let the sum of money be rs. P
Then,
$$\eqalign{
& \Rightarrow \left[ {P{{\left( {1 + \frac{R}{{100}}} \right)}^t} - P} \right] = {\text{C}}{\text{.I}}{\text{.}} \cr
& \Rightarrow \left[ {P{{\left( {1 + \frac{{10}}{{100}}} \right)}^2} - P} \right] = 525 \cr
& \Rightarrow P{\left( {\frac{{11}}{{10}}} \right)^2} - 1 = 525 \cr
& \Rightarrow P\left( {\frac{{121}}{{100}} - 1} \right) = 525 \cr
& \Rightarrow P\left( {\frac{{21}}{{100}}} \right) = 525 \cr
& \Rightarrow P = \frac{{525 \times 100}}{{21}} \cr
& \Rightarrow P = {\text{Rs}}{\text{.}}\,2500 \cr
& \therefore {\text{ Sum of money}} \cr
& {\text{ = Rs}}{\text{. 2500}} \cr} $$
Simple interest on the same sum Rs. 2500 for 4 (double the time) years at 5% (half the rate of percent per annum) is
So,
$$\eqalign{
& {\text{S}}{\text{.I}}{\text{. = Rs}}{\text{.}}\left( {\frac{{2500 \times 5 \times 4}}{{100}}} \right) \cr
& \,\,\,\,\,\,\,\,\,{\text{ = Rs}}{\text{. 500}} \cr} $$