Both mixtures 'A' and 'B' contain milk and water.

Solution

Quantity of water in the container = 600 X (5/12) = 250 litres
So, quantity of water in the two mixtures together = 250 - 50 = 200 litres
So, quantity of water in each mixture = 200 ÷ 2 = 100 litres
For I:
Let the total quantity of mixture 'A' be 'x' litres.
ATQ;
0.25x = 100
So, x = 400
So, quantity of mixture 'B' = 600 - 50 - 400 = 150 litres
So, quantity of milk in mixture 'B' = 150 - 100 = 50 litres
So, statement I is true.
For II:
Let the total quantity of mixture 'A' be 'x' litres.
ATQ;
0.4x = 100
So, x = 250
So, quantity of mixture 'B' = 600 - 50 - 250 = 300 litres
So, quantity of milk in mixture 'B' = 300 - 100 = 200 litres
So, statement II is true.
For III:
Let the total quantity of mixture 'A' be 'x' litres.
ATQ;
0.5x = 100
So, x = 200
So, quantity of mixture 'B' = 600 - 50 - 200 = 350 litres
So, quantity of milk in mixture 'B' = 350 - 100 = 250 litres
So, statement III is true.