A corrupt rice vendor uses a weight of 1200 grams instead of 1 kg while buying rice and use a weight of 900grams instead of 1 kg while selling it also add 5 kg of white stone per 100 kg of rice to get a more money if he gives a discount of 10% to his customer on cost price then how much profit does he makes?

Let's assume that the cost price of rice is Rs 1000/kg. And let's decode the problem step by step.
(1) The vendor is corrupt so, he will eventually get 1200 gm of rice for 1000 Rs. Thus this (Rs 1000/ 1200 gm) is what vendor purchases the rice in.

(2)Now, he mixes 5 kg stones with 100 kg rice, which means that every 105 kg mixture that he sells; the mixture will only have 100 kg rice.

(3) Further he gives a discount of 10% on the cost price (1000 Rs/kg) which means his selling price will be (900 Rs/kg). But he is corrupt and will eventually give only 900 gm of 'mixture' to the customer at 900 Rs. Thus the customer gets only (900*100/105 = 857.14 gm) of rice for 900 Rs.

(4) Now, in order to compare the profit, let's equalize the amount spent by the vendor and customer. Thus vendor spent (1000 Rs) and got (1200 gm rice). While customer on spending (1000 Rs) will get (857.14*1000/900 = 952.37 gm rice).

(5) Thus the % profit of vendor = (Goods left/Goods Sold)*(100) = (1200-952.37)/(952.37)*100 = 26%.

-> Thus the approximate answer to the question is 26%.
Hope this solves your doubt.

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