Question

by selling 100 biscuit packets a shopkeeper makes a profit equivalent to the selling price of 40 biscuit packets. find his gain percent.

Answer 1

$$\begin{gathered} \mathrm{Let}\mathrm{SP}\mathrm{of}1\mathrm{biscuit}=\mathrm{Rs}\mathrm{x} \\ \mathrm{So},\mathrm{SP}\mathrm{of}100\mathrm{biscuits}=\mathrm{Rs}100\mathrm{x} \\ \mathrm{A}.\mathrm{T}.\mathrm{Q} \\ \mathrm{Profit},\mathrm{P}=\mathrm{Rs}40\mathrm{x} \\ \mathrm{We}\mathrm{know}\mathrm{that}\mathrm{P}=\mathrm{SP}-\mathrm{CP} \\ 40\mathrm{x}=100\mathrm{x}-\mathrm{CP} \\ \mathrm{CP}=100\mathrm{x}-40\mathrm{x} \\ \mathrm{CP}=\mathrm{Rs}60\mathrm{x} \\ \mathrm{Gain}\%\mathrm{or}\mathrm{Profit}\%=\left[\frac{\mathrm{Profit}}{\mathrm{CP}}\times 100\right]\% \\ =\left[\frac{40\mathrm{x}}{60\mathrm{x}}\times 100\right]\% \\ =66.7\% \end{gathered}$$