A faulty weighing machine reads 1 kg when 900 gm is actually weighted on it. The shopkeeper marked the price of his goods by 10%, but unfortunately he was caught by the metrology department and then they ordered him to repair his weighing machine and gave punishment to sell the goods at 10% discount on cost price for a month. If each customer is now paying ₹20 for 1 kg, then before the raid _______ amount they have paid for the same quantity. (Rounded off to two places of decimal)

₹27.16

According to the question,

It is given that initially, weighing machine weighs 900 gm instead of 1000 gm

So, it means shopkeeper earns 100 gm profit on  selling 900 gm goods 

= Profit % = Profit/C.P. × 100 

= Profit% = 100/900 × 100 = 11.11%

So, he earns this by alteration of weight along with he marked up the price by 10% 

Means his overall profit can be calculated by successive 

Overall profit = 11.11 + 10 + (11.11 × 10)/100 = 22.22%

But , now the shopkeeper sells the goods at Rs20 per kg after giving 10% discount

Actual Cost price of 1kg sugar = 100 /(100 - 10) × 20 = 100/90 × 20 = Rs22.22

And earlier shopkeeper was selling at 22,22% profit 

So, Selling price = (100 + 22.22) /100 × 22.22 

= 122.22/100 ×22.22 = Rs27.157  =  Rs. 27.16