GMAT Exam: A Simple Guide To Solving Word Problems - Mixtures

In a mixture problem, the amount (or value) of a substance before mixing equals the amount (or value) of that substance after mixing.

Make a table to organize the mixture information to help you understand the question.


Example: How many milliliters of a 30% alcohol solution must be added to 500 milliliters of a 70% alcohol solution to yield a 40% alcohol solution?
Let x = the number of milliliters of the 30% solution to be added.
Make a table to organize the information in the question.

The amount of alcohol before mixing equals the amount of alcohol after mixing.

Write an equation that represents the facts shown in the table.
30%x + 70%(500) = 40%(x + 500)

Solve the equation.

1,500 milliliters of the 30% alcohol solution must be added.