By selling 12 kg of potatoes for 63, a shopkeeper gains 5%. What does his gain or loss percent by selling. 50 kg of the same potatoes for 247.50 ?

Answer: Option B

Selling price of 1 potatoes
$$\begin{array}{rl}& =\text{Rs}\text{.}\frac{63}{12}\\ & =\text{Rs}\text{.}\frac{21}{4}\\ & \text{CP}\times \frac{\left(100+\text{P}\right)}{100}=\text{SP}\\ & \text{CP}\times \frac{105}{100}=\frac{21}{4}\\ & \text{CP}=\text{Rs}\text{. 5}\end{array}$$
Gain or loss percent by selling 50 kg of the same potatoes for Rs. 247.50
Cost price of 50 kg potatoes
= 50 × 5
= Rs. 250
Loss = 250 - 247.50 = Rs. 2.50
$$\begin{array}{rl}& \text{Loss }\%=\frac{2.50}{250}\times 100\\ & =1\%\end{array}$$