A rectangular tank measuring 5 m x 4.5 m x 2.1 m is dug in the centre of the field measuring 13.5 m x 2.5 m . The Earth dug out is spread evenly over the remaining portion of the field. How much is the level of the field raised?

Let quantity of mixture be x liters.

Suppose a container contains x units of liquid from which y units are taken out and replaced by Water. After operations , the quantity of pure liquid =  x 1 - y x n units, Where n = no of operations . 

So, Quantity of Milk =  x 1 - 6 x 2  

Given that, Milk : Water = 9 : 16 

=> Milk : (Milk + Water) = 9 : (9+16)

=> Milk : Mixture = 9 : 25 

 Therefore,  x 1 - 6 x 2 x = 9 25

=> x = 15 liters

Let the capacity of the pot be 'P' litres.
Quantity of milk in the mixture before adding milk = 4/9 (P - 8)
After adding milk, quantity of milk in the mixture = 6/11 P.
6P/11 - 8 = 4/9(P - 8)
10P = 792 - 352 => P = 44.

The capacity of the pot is 44 liters.