How much pure antifreeze must be added to 12 gallons of 20% antifreeze to make a 40% antifreeze solution?

Question

Quizplus · Accepted Answer

Let X be the amount of pure antifreeze needed to be added.

Initial antifreeze amount = 20% of 12 gallons = 2.4 gallons

Final antifreeze amount = 40% of (12+X) gallons

Using the formula for concentration, we can equate the two:

2.4 + X = 0.4(12+X)

Solving for X gives us X=4 gallons. Therefore, we need to add 4 gallons of pure antifreeze to make a 40% antifreeze solution.

How Much Pure Antifreeze Must Be Added to 12 Gallons