How many liters of pure alcohol must be added to a 100liter solution that is 20 percent alcohol in order to produce a solution that is 25 percent alcohol?
(A) 7/2
(B) 5
(C) 20/3
(D) 8
(E) 39/4
PLS EXPLAIN
Percentge
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 Junior  Next Rank: 30 Posts
 Posts: 13
 Joined: 15 Jun 2008
here is what I did...
assuming pure alcohol is 100% proof, let's call the content to be added 1.00n
algebraic expression:
let n replace what is being added...
100%n + (20%)100liters = 25% (n+100liters)
1n + (0.2)100 = 0.25 (n+100)
1n + 20 = 0.25n + 25
1n  0.25n = 25  20
0.75n = 5
3/4n = 5
n = 20/3
not too sure....but I like to think I got it right
assuming pure alcohol is 100% proof, let's call the content to be added 1.00n
algebraic expression:
let n replace what is being added...
100%n + (20%)100liters = 25% (n+100liters)
1n + (0.2)100 = 0.25 (n+100)
1n + 20 = 0.25n + 25
1n  0.25n = 25  20
0.75n = 5
3/4n = 5
n = 20/3
not too sure....but I like to think I got it right