Question

How much per cent above the cost price should a shopkeeper mark his goods so that after allowing a discount of 10% on the marked price, he gains 8%?

Answer 1

Let $Rs100$ be the cost price.
Gain required = 8%
Therefore, the selling price is $Rs108$.
Let $Rsx$ be the marked price.
Then, discount = 10% of x
$$\begin{gathered} =\frac{10}{100}\times x \\ =\frac{x}{10} \end{gathered}$$
Selling Price = MP − discount
$$\begin{gathered} \Rightarrow 117=x-\frac{x}{10} \\ \Rightarrow 117=\frac{9x}{10} \end{gathered}$$

$$\begin{gathered} \Rightarrow 9x=1080 \\ \Rightarrow x=\frac{1080}{9} \\ \Rightarrow x=120 \end{gathered}$$

∴ Marked price = $Rs120$

Hence, the marked price is 20% above the cost price.