You need 630 mL of a 50% alcohol solution. On hand, you have a 10% alcohol mixture. How much of the 10% alcohol mixture and pure alcohol will you need to obtain the desired solution?

Answer 1

x ml amount of 10% alcohol

(630-x) ml amount of pure alcohol

total 630 ml 50% alcohol

0.1 x + (1)630-x = 630 * 0.5

0.1x + 630 - x = 315

-0.9x = -315

x = 350 ml 10% alcohol

630 - 350 = 280 ml pure alcohol