A dishonest seller sells goods at 4% loss on cost price

Solution

Suppose the cost price is Rs. x per kg. Then, he sells the goods for Rs. x * (100 – 4)/100 = Rs. 96x/100 per kg Now, suppose he bought y kg of goods. Then, his total investment = Rs.xy And his total return = 96x/100 * y(20/18) = Rs. 96 xy/90 Profit% = (96xy/90 – xy)/xy * 100 = (6 * 100)/90 = 6.67% Alternate Method: x = loss%, y = true weight, z = false weight (100 – x) * z/y – 100 = (100 – 4) * 20/18 – 100 = 96 * 20/18 – 100 = 106.67 – 100 = 122/11 = 6.67% Since the sign is positive, there is a profit.