A seller cheats his supplier and his customer by using false weights. When he buys from the supplier, he takes 8\(\frac{1}{3}\)% more than the indicated weight. When he sells to his customer, he gives 8\(\frac{1}{3}\)% less than the indicated weight. If he sells his articles at the cost price, then find his net profit percent.

18\(\frac{2}{11}\)%

Let actual weight = 100 gm

At the time of buying = 100 × \(\frac{13}{12}\) (8\(\frac{1}{3}\)% = \(\frac{1}{12}\))

= \(\frac{1300}{12}\) gm

At the time of selling = 100 × \(\frac{11}{12}\)

                               = \(\frac{1100}{12}\)

Profit % = \(\frac{\frac{1300}{12} - \frac{1100}{12}}{\frac{1100}{12}}\) x 100 = 18\(\frac{2}{11}\)%