Word Problems Mixture Mock Tests

A 12-liter solution contains 20% salt. How much water must be added to make the salt concentration 15%?

A mixture of 20 liters contains 10% alcohol. How much pure alcohol must be added to make the concentration 20%?

A 20-liter solution contains 25% acid. How many liters of pure acid must be added to make the solution 40% acid?

A solution is 20% alcohol by volume. If 4 liters of water are added to 12 liters of this solution, what is the new percentage of alcohol by volume in the resulting solution?

A 20-liter solution contains 30% alcohol. How many liters of pure water must be added to reduce the alcohol concentration to 20%?