If selling price is doubled, the profit triples. Find the profit percent.

Answer: Option B

$$\begin{array}{rl}& \text{Let}\text{C}\text{.P}\text{.}\text{be}\text{Rs}\text{.}x\text{and}\text{S}\text{.P}\text{.}\text{be}\text{Rs}.y\\ & \text{Then},3\left(y-x\right)=\left(2y-x\right)\\ & \Rightarrow y=2x\\ & \text{Profit}=Rs.\left(y-x\right)\\ & =Rs.\left(2x-x\right)\\ & =Rs.x\\ & \therefore \text{Profit}\%\\ & =\left(\frac{x}{x}\times 100\right)\%\\ & =100\%\end{array}$$