Question

The cost price of 10 articles is equal to the selling price of 9 articles. Find the profit percentage.

Answer 1

CP of 1 article is x.
CP of 10 articles is 10x = SP of 9 articles.
CP of 9 articles = 9x
Profit = SP−CP
= 10x − 9x
= x
$\text{Profit}\left(\%\right)=\frac{\text{profit}\times 100}{\text{CP}}$
$=\frac{x\times 100}{9x}$
$=11\frac{1}{9}\%$