You need 330mL of a 25% alcohol solution. On hand, you have a 30% alcohol mixture. How much of the 30% alcohol mixture and pure water will Will you need to obtain the desired solution?

Answer 1

Let x = the amount of 30% solution

330-x = the amount of water

So,

(30x + (330-x)(0))/(x + (330-x) ) = 25

From this, you get

x = 275 ml of the 30% solution

330-x = 55 ml of water

(275 + 55 = 330)