Mathematics · Profit and Loss

A businessman considers four different methods to maximize his profit on an item. Which of the following methods yields the highest profit percentage? I. Sell the item at a flat 10% profit. II. Use an incorrect weight which is 100 grams less than 1 kg, but mark and sell it as 1 kg. III. Mix 10% impurities in the item and sell the mixture at the cost price of the pure item. IV. Increase the price by 5%, and use an incorrect weight whose real value is 5% less than what is marked on it.