Discussion

Explanation:

A shopkeeper cheats while buying as well as while selling. while buying he pays for 20% less than what he takes and while selling he charges for 20% more than what he gives. If his selling price per kg is 10% less than his cost price per kg, what is his (approximate)  profit percentage?

Given, his selling price per kg is 10% less than his cost price per kg
∴ Multiplication factor for price = 9/10

While buying if he takes 1000 gms, he pays for only 800 gms.
⇒ multiplication factor while buying = 1000/800 = 5/4

While selling if he gives 1000 gms, he charges for 1200 gms.
⇒ multiplication factor while selling = 1200/1000 = 6/5

∴ Overall multiplication factor for quantity = 5/4 × 6/5 = 3/2

⇒ Overall multiplication = 3/2 × 9/10 = 27/20 = 1.35

∴ % profit = (1.35 - 1) × 100% = 35%

Hence, option (b).

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