Question

2. A chemist wants to make 4 liters of a 7% acid solution by mixing a 10% acid solution and a 4% acid solution. How many liters of each solution should the chemist use? Write your answer as a complete sentence. Be sure to: • Define your variable and expressions for the quantities. • Write an equation that models the problem. • Solve the equation. • State the answer in a complete sentence.

Answer 1

Let x be the 10% solution and y be the 4% solution.
.1x + .04y = .07(4)
x + y = 4
These are the two equations. 
Solve the equations.
.6y = 1.2
y = 2
Plug this back into the second equation to get x = 2. 

Therefore the Chemist must mix 2 liters of the 10% solution with 2 liters of the 4% solution to get 4 liters of the 7% solution.