The Profit Gained by a Shopkeeper who Uses an 800gm Weight Rather than a Kilogram weight A shopkeeper professes to sell his goods at $200 but uses a weight of 800gm instead of kilogram weight. Thus, he makes a profit of The choices are as follow: 20% 22% 25% None of these The answer key shows that the answer is 25% (from the solution 200/800 x 100)%. However, I think that if the shopkeeper wants to make a profit, he should make use of a kilogram weight which has an additional 200gm instead of an 800gm weight because if that is so, as stated in the problem, the shopkeeper would have a 20% loss rather than 20% gain. Please help me understand this problem. I can't reconcile my thoughts with the given answer key. PS I'm a college student having troubles with word problems.

The (crooked) shopkeeper is selling $800g$ worth of goods as if it were $1kg (=1000g)$.

Hence he's charging $\frac{1000}{800} = 1.25$ times more than he should be (if he were honest).

That's $25$% (dishonest) profit.

Usually, weighing of goods is done in front of the customer. By substituting an actually lower standard weight for a higher one (in a balance scale), the shopkeeper is giving the impression that the goods the customer is buying weigh more than they actually do (so the customer will be deceived into paying more than he/she should).