If a man estimates his loss as 20% of the selling price, then his loss percent is = ?

Answer: Option D

According to the question,
Loss = 20% Selling price
$$i.e.\frac{\text{Loss}}{\text{Selling price}}=\frac{1}{5}$$
∴ Cost price = Selling price + Loss
= 5 + 1
= 6
$$\begin{array}{rl}& \therefore \text{Loss}\%=\frac{1}{6}\times 100\\ & =\frac{50}{3}\%\end{array}$$