A dishonest shopkeeper promises to sell his goods at cost price. However, he uses a weight that actually weighs 21% less than what is written on it. Find his profit percentage.

Correct option is B

Given:

Shopkeeper claims to sell at cost price

He uses weights that are 21% less than the marked weight

Concept Used:
The shopkeeper gives less quantity than he claims, but charges full price. This results in a gain, which is calculated based on actual quantity given.

Formula Used:

Profit % = $$\left( \frac{\text{Gain}}{\text{Cost Price}} \right) \times 100$$​​

Solution:

Let actual weight given = 100 – 21 = 79% of the claimed weight
So, shopkeeper gives only 79 units instead of 100, but charges for 100

Profit % = $$\left( \frac{100 - 79}{79} \right) \times 100$$​​

​$$= \left( \frac{21}{79} \right) \times 100$$​​

​$$= 26\frac{46}{79}\%$$​​