Q) A chemist adds two quarts of pure alcohol to a 30% solution of alcohol in water. If the new concentration is 40%, how many quarts of the original solution were there?
(A) 12
(B) 15
© 18
(D) 20
(E) 24
Bump^
OK, for starters, why bump immediately after posting the question?
This type of problem is called “Percent Mixture.” Here’s an explanation: http://purplemath.com/modules/mixture.htm
I teach it using a chart: # quarts x percent pure = total.
For the pure alcohol: 2 quarts x 1 (100% = 1) = 2
for the solution: x quarts x .30 = .3x
for the mixture: (2+x) quarts x .40 = .40(2+x)
your equation is 2 + .3x = .4(2+x)
distribute and eliminate the decimals: 20 + 3x = 8 + 4x
x=12
@bjkmom, thank you for the response 
your answer gave me some clarity.
MODERATOR’S NOTE:
Question removed - duplicated in another thread.
gcf101
P.s, I bumped it almost immediately because I was out of time.
Just as a friendly FYI… adding that bump accomplishes nothing. Your first post was at the top of the “Latest Posts” list. Your bump 30 seconds later did absolutely nothing.
You posted at 8:16 on the Eastern Seaboard on a Sunday morning. Many of the people you were looking to for help were in bed. (I’m a NY morning person who had kids to get up for church.)
I’ve got to ask: On 8:16 on a Sunday morning— out of time for what?
First, second @bjkmom.
And second, let me Google that for you:
http://bfy.tw/3mfB
@gcf101, google what?
@bjkmom, I’m fairly new to college confidential which is why I dont have complete knowledge of how it works. I thought extra comments (or in my case,bumping) help my post get a little more visibility. And I’m taking the SAT in 4 days so I dont have much time. Thank you for your response.
I figured it was something like that.
But, honestly, on a Sunday morning, it’s not getting too much visibility no matter what you do. Remember that the vast number of members here are high school and college kids, and Sunday morning is probably not the best time to catch them-- or to catch them at their best, anyway.
And I understand that it’s hard to google a problem when you don’t even know what it’s called; that’s why I gave you the title along with the link.
One more piece of math teacher/mom advice: know that cramming with 4 days left before the SAT is very, very unlikely to do anything but stress you out. At this point in your academic career, you know what you know.
Either you’re a Senior, and you’ve already taken the exam at least once (in which case you already HAVE a score) or you’re a Junior, panicking about the new exam. (In which case, breathe!! Your entire grade will take the new exam. If it’s harder, it’s harder for everyone. What will matter is what has always mattered: your percentile.)
So enjoy the day off if you have it, take deep breaths, and simply go take the test. That’s all it is: a test, like the hundreds of other tests you’ve taken. You’ll do the way you’ve always done, and find a college that’s suited for you.
@bjkmom Your advices and explanations are truly valuable. At the same time, I find it important that people try to think on their own first before posting a Mayday distress call for help.
As for how hard it is to google a problem - you don’t always need to know the type of a problem; often it’s enough to just type (or copy and paste) a line from the problem (as in “A chemist adds two quarts of pure alcohol to a 30% solution of alcohol in water”) into Google (or simply into the url line) and hit enter.
I don’t think OP is from the US, but @rahuilmars you should take that into account. You posted at 08:16 EST Sunday, which is 05:16 PST, so you’d be less likely to get a response.
And yes, always Google it first!