By selling 4 articles for 1 rupee, a man losses 4%. Had he sold three articles per rupee, the profit would have been = ?

Answer: Option B

Selling price of 4 article = Rs. 1
Loss = 4%
Cost price of 4 articles
$$\text{ = 1}\times \frac{100}{96}=\frac{100}{96}$$
Cost price of 3 articles
$$\text{ = }\frac{100}{96}\times \frac{3}{4}=\frac{75}{96}$$
New selling price of 3 articles = Rs. 1
$$\begin{array}{rl}& \text{Profit }\%\\ & =\frac{\frac{1-75}{96}}{\frac{75}{96}}\times 100\\ & =\frac{21}{75}\times 100\\ & =28\%\end{array}$$