Question

You need 300 mL of a 65% alcohol solution. On hand, you have a 50% alcohol mixture. How much of the 50% alcohol mixture and pure alcohol will you need to obtain the desired solution?

You will need
____ mL of the 50% solution
and
______ mL of pure alcohol.

Answer 1

You will need 220 mL of the 60% solution and 80 mL of pure alcohol.

Explanation:

Let 'x' be the amount of 50% alcohol solution and y the amount of pure alcohol.

Therefore:

(0.5x + y)/300 = 0.65 ⇒ 0.5x + y = 190

x + y = 300

Solving the sistem of equations:

x = 220 and y = 080

Therefore, You will need

220 mL of the 60% solution

and 80 mL of pure alcohol.