"Published in Newark, California, USA"
A Chinese wine merchant has a cask full of brandy. He draws 5 liters and fills the cask with water. Once again, he draws out another 5 liters and fills the cask with water. How many liters does the cask hold if there are now 16 liters of brandy left?
Solution:
The given word problem describes the dilution of a substance which is a brandy with water. A certain amount of brandy is drawn from the cask and replaced with the equal amount of water. Let's analyze the word problem as follows
Let x = be the amount of brandy in liters before it is drawn
x = be the volume of the cask or container in liters
Amount of brandy at the first drawn
Amount of brandy at the second drawn
The terms inside the bracket is the amount of the brandy left after the first drawn.
Multiply both sides of the equation by x, we have
Using Quadratic Formula,
Choose the positive sign because the initial amount of brandy must be more than 16 liters
Therefore, the amount of brandy before it is drawn is 25 liters. This is also the volume or size of the cask.