How many liters of a 10% alcohol solution must be mixed with 90 liters of 70% solution to get a 60% solution?

Question

How many liters of a 10% alcohol solution must be mixed with 90 liters of 70% solution to get a 60% solution?

Answer 1

First, % is converted to decimal for all three solutions. Then use a modified M₁V₁=M₂V₂ equation.

(0.70 * 90) + (0.10 * X) = 0.60(90 + X)

63 L + 0.10X = 54 + 0.60X

9 = 0.50X

X = 18 L