Container A has a base measuring 30 cm by 10 cm and it contains 4.2 litres of juice. Container B has a square base with side 10 cm and it is filled with juice to a height of 8 cm. Juice from Container A is poured into Container B until the height of juice in Container A is 1/2 that of Container B. What is the height of juice in Container B in the end?
