A dishonest shopkeeper uses a false weight of 900gm instead of 1kg, if he promises to sell his goods at cost price, what is his overall profit?
I approached this problem like this,
when a customer buys 1 kg, he gets 0.9 kg.(profit of 0.1kg for shopkeeper)
when a customer buys 2 kg, he gets 1.8 kg.(profit of 0.2kg for shopkeeper)
So, if the shopkeeper has x kg originally, he will be able to sell (10x/9)kg.
It gives me the correct answer but I still can't visualize this.
For e.g. Let's say the shopkeeper has 9 kg originally, and sells all of it, in this case he will sell 8.1 kg(there is 900gm left). So, in total he will sell, 9.9kg(9kg+900gm leftover). The earlier equation gives 10kg.
What is wrong with reasoning?