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After 200 grams of water were added to the 24% solution of

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CEO
Joined: 21 Jan 2007
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Location: New York City
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After 200 grams of water were added to the 24% solution of [#permalink]  17 Oct 2007, 12:31
After 200 grams of water were added to the 24% solution of alcohol, the strength of the solution went down by 1/3. How much of the 24% solution was used?

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VP
Joined: 08 Jun 2005
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see attachment:

Since we added 200 grams of water, and got a ratio of 16:8 = 2:1 then the solution had to be 400 grams and the answer should be (E)

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CEO
Joined: 21 Jan 2007
Posts: 2760
Location: New York City
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Kudos [?]: 387 [0], given: 4

What is the algebraic setup?
Manager
Joined: 22 May 2007
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A - total grams of alcohol
X - total grams of original solution

.24X=A

.16(x+200)=A

X=400
SVP
Joined: 04 May 2006
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Schools: CBS, Kellogg
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KillerSquirrel wrote:
see attachment:

Since we added 200 grams of water, and got a ratio of 16:8 = 2:1 then the solution had to be 400 grams and the answer should be (E)

Thank KillerSquirrel, this method is very useful.
VP
Joined: 09 Jul 2007
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Location: London
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let's start it from water side

0.76Y+200=0.84(Y+200)

Y=400 grams
Senior Manager
Joined: 04 Jun 2007
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KillerSquirrel wrote:
see attachment:

Since we added 200 grams of water, and got a ratio of 16:8 = 2:1 then the solution had to be 400 grams and the answer should be (E)

I like this method but from the diagram the ratio of water to alcohol is 2:1 which means there's twice as much water as alcohol right?
so if there is 200g of water, shouldn't there be 100g of alcohol??
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