A dishonest shopkeeper, at the time of selling and purchasing, weighs 10% less and 20% more per kilogram respectively. Find the percentage profit earned by treachery. (Assuming he sells at Cost Price)

Answer: Option D

While purchasing he would take 1200 grams for the price of 1000 grams. While selling he would sell 900 grams for the price of 1000 grams.
Since, CP = SP
The profit earned by him,
$$\frac{\text{Goods Left}}{\text{Goods Sold}}=\frac{300\times 100}{900}=$$       $$33.33\%$$