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					 A shopkeeper buys 26 liter of milk @ Rs. 16 per liter. He also buys from another source an inferior quality of milk @ Rs. 10 per liter. How much quantity of the later should he buy to mix it with the former so that he can sell the mixture @ Rs. 14 per liter without making any loss?
 
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- 13 liter
 - 12 liter
 - 14 liter
 - 16 liter
 
 
Correct Option: A
Quantity of milk @ Rs.10 per liter / Quantity of milk @ Rs. 16 per liter = 1 / 2 
So, quantity of milk @ Rs. 10 per liter = 26 / 2 = 13 liter.
2nd Method 
Let us assume shopkeeper buy P liter milk of price @ Rs. 10 per liter.
Buy price of 26 liter of milk @ Rs. 16 per liter = 26 x 16
Buy price of P liter of milk @ Rs. 10 per liter = P x 10
Sell price of  total milk ( P + 26 ) @ Rs. 14 per liter = 14 x ( P + 26 ) 
According to question there is no loss or no profit.
Then Buy Price = Sell Price 
26 x 16 + P x 10 = 14 x ( P + 26 ) 
⇒  26 x 16 + 10P = 14P + 14 x 26 
⇒  26 x 16 -  26 x 14  = 14P - 10P
⇒  2 x 26   = 4P
⇒  4P = 2 x 26
⇒  P = 2 x 26 / 4 = 13
So, quantity of milk @ Rs. 10 per liter = 13 liter.