You need 380 mL. 60% alcohol solution. 5% alcohol mixture.

Question

You need 380 mL of a 60% alcohol solution. On hand, you have a 5% alcohol mixture. How much of the 5% alcohol mixture and pure alcohol will you need to obtain the desire solution? 

Answer 1

If we let x = the amount of 5% solution and y = the amount of pure alcohol, we can set up that

 

.05x+y is the amount of alcohol in our resulting mixture, and x+y is the total amount in our resulting mixture (which we know is 380)

 

so we also know that:

(.05x+y)/380 = .6

 

If we simplify this we come up with:

.05x+y=228

and we know x+y=380

 

If we solve this as a system of equations, we will find that:

x=160 ml

y=220 ml