The Banker Gain on a certain sum 4 years hence at 5% is Rs. 200. What is the present worth?

Answer: Option C

T = 4 years
R = 5%
Banker's Gain, BG = Rs. 200
$$\begin{array}{rl}& TD=\frac{BG\times 100}{TR}\\ & =\frac{200\times 100}{4\times 5}\\ & =\text{Rs}\text{.}1000\\ & \\ & TD=\sqrt{PW\times BG}\\ & 1000=\sqrt{PW\times 200}\\ & 1000000=PW\times 200\\ & PW=\frac{1000000}{200}\\ & =\text{Rs}\text{. }5000\end{array}$$