The compound interest on Rs. 4000 for 4 years at 10% per annum will be = ?

Answer: Option A

$$\begin{array}{rl}& \text{10}\%\text{ = }\frac{1}{10}\\ & \text{Principal}\text{Amount}\\ & \text{10}11\\ & \text{10}11\\ & \text{10}11\\ & \text{10}11\\ & \underset{\text{CI = 4641}}{\underbrace{\overline{10000\text{:}\text{14641}}}}\\ & \because \text{Principal = 10000 units}\\ & \text{ = Rs}\text{. 4000 (given)}\\ & \text{1 unit = }\frac{2}{5}\\ & \text{CI = 4641 unit}\\ & \text{ = Rs}\text{. }\left(\frac{2}{5}\times 4641\right)\\ & =\text{Rs}\text{. }1856.40\end{array}$$