Question

LeBron needs 150 milliliters of a 30% solution of sulfuric acid for a lab experiment but only has access to a 25% and a 50% solution. How much of the 25% and how much of the 50% solution should he mix to make the 30% solution?

Answer 1

• 30 mL of 50% solution
• 120 mL of 25% solution

Explanation:

Let x represent the amount of 50% solution LeBron needs. Then (150-x) is the amount of 25% solution, and the total amount of acid in the mix is ...

50%(x) +25%(150 -x) = 30%(150)

.25x + 37.5 = 45 . . . . . simplify

.25x = 7.5 . . . . . . . . . . . subtract 37.5

x = 7.5/.25 = 30 . . . . divide by the coefficient of x; mL of 50% solution

150-x = 120 . . . . . . . . mL of 25% solution

LeBron should mix 120 mL of 25% solution with 30 mL of 50% solution to make the 30% solution.