A jar is filled of liquid which is 3 parts water and 5 parts alcohol. How much of this mixture should be drawn out and replaced such that this mixture may contain half water and half alcohol?
Answer: B
Let the jar initially contain 8 liters of mixture:3 liters water and 5 liters alcohol
Let x liters of this mixture is drawn out and is replaced by x liters of water.
Amount of water now in the solution: 3-(3/8)x+x.
Amount of alcohol now in the solution: 5-(5/8)x
Desired ratio: 1/1
=>3-(3/8)x+x=5-(5/8)x
x=8/5 liters
%x=((8/5)/8) × 100=20%