<PRE><B>Question 370860</B>
You have a 68% alcohol solution.
 You want to end up with a solution containing 50% alcohol.
:
Add pure water, let w = amt of water, start with 10 liters of 68% solution
:
.68(10) = .50(w+10)
6.8 = .5w + 5
6.8 - .5 = .5w
1.8 = .5w
multiply both sides by 2
w = 3.6 liters of water added to 10 liters of 68% solution yields 13.6 liters of 50% solution
:
:
Check this, the amt of alcohol will remain the same; only the per cent changes
.68(10) = .5(13.6)
6.8 = 6.8</PRE>