college algebra

Question

You need a 5% alcohol solution. On hand, you have a 35 mL of a 50% alcohol mixture. How much pure water will you need to add to obtain the desired solution?A) Write an equation using the information as it is given above that can be used to solve this problem. Use as your variable to represent the amount of pure water you need to use.Equation:    

 B) You will need  ? mL of pure water to obtain  ?  mL of the desired 5% solution.

Answer 1

The alcohol content is 0.5*35 + 0 * x = (x+35)*0.05

17.5 = 0.05x + 1.75

15.75 = 0.05 x

x = 315

check:

mixing all of the 50% alcohol solution with 315 ml of water results in 350 mL solution,

17.5 mL of which is alcohol. 17.5/350 = 0.05 = 5%

Mix 315 mL of water with all of the 50% alcohol solution