If the lab technician needs 30 liters of a 25% acid solution, how many liters of the 10% and the 30% acid solutions should she mix to get what she needs? enter your answer. check answer

7.5 L of the 10% and 22.5 L of the 30% acid solution, she should mix.

Explanation:

Let the volume of 10% acid solution used to make the mixture = x L

So, the volume of 30% acid solution used to make the mixture = y L

Total volume of the mixture = x + y = 30 L (1)

For 10% acid solution:

C₁ = 10% , V₁ = x L

For 30% acid solution :

C₂ = 30% , V₂ = y L

For the resultant solution of sulfuric acid:

C₃ = 25% , V₃ = 30 L

Using  

C₁V₁ + C₂V₂ = C₃V₃

10×x + 30×y = 25×30

So,  

x + 3y = 75 (2)

Solving 1 and 2 we get,

x = 7.5 L

y = 22.5 L