Question

You need 135 mL of a 25% alcohol solution. On hand, you have a 45% alcohol mixture. How much of the 45% alcohol mixture and pure water will you need to obtain the desired solution?

Answer 1

Explanation:

One needs 135mL of a 25% alcohol solution. This is equivalent to saying one needs 0.25(135mL) = 33.75mL of alcohol.

Hence, amount of 45% alcohol mixture needed = 33.75ml/(0.45) = 75mL.