The cost price of 10 articles is equal to the selling price of 9 articles. Find the gain percent.
Let the C.P. of 1 articles =Rs.1.
∴ The C.P. of 10 articles =1×10=Rs.10
∴ S.P. of 9 articles= C.P. of 10 articles
∴ S.P. of 9 articles=Rs.10
Hence, we calculate the cost of 9 articles,
C.P. of 9 articles=1×9
=Rs.9
∴Profit=S.P.−C.P.
Profit=10−9
Profit=Rs.1
∴Profit%=ProfitC.P.×100
Profit%=19×100
Profit%=11.11%.