ratio and mixture in 1 prob

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ratio and mixture in 1 prob

by deagez » Sat Aug 08, 2009 12:22 pm
solution a is 20% salt and solution b is 80% salt. If you have 30oz of solution a, and 60oz of solution b, in what ratio can you mix solution a with solution b to produce 50oz of a 50% solution?

a) 6:4
b) 6:14
c) 4:4
d) 4:6
e) 3:7
Source: — Problem Solving |

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by barnum » Sat Aug 08, 2009 8:35 pm
Can we start a policy that people should always post where they find these questions? I think it would be helpful to begin figuring out where the bulk of the good fake questions are versus the bad fake questions (especially because there are so many bad fake ones).

The answers here, for example, are not written in their lowest form, which GMAT would always do on a ratio. Not to mention the question itself makes little sense.

But to answer it anyway, if you have two solutions, one that is 20% and another is 80% and you want the result of the mixture to be at 50%, which is the exact average, this will occur as long as the two mixtures are mixed in a 1:1 ratio. Given the answer choices, this would be C because 4:4 is the same as 1:1

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by deagez » Sun Aug 09, 2009 11:16 am
This is from a Veritas Prep online exam.

I agree this question sucks really bad. But I found the bulk of their questions are great.

Thanks for the explanation.

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by barnum » Sun Aug 09, 2009 6:18 pm
No problem.

And it was just a general thought I had been having as I have been reading this board. Due to the limited quantity of real questions that are available, it is not surprising that many people turn to fake questions for additional practice. I was also noticing though that many of these fake questions are frankly poorly written, do not represent what the GMAT actually tests, are hard in the wrong ways, etc.

So I was thinking that if we could start a trend of people posting not only the questions, but also where they are finding them, we may be able to discern which companies or more worthwhile than others in terms of using their fake questions. Just a simple, "I found this question at ..." at the start of the posted question. This would, I think, be helpful to everyone in the long run.

So I am just trying to start this trend throughout the forum beginning with this post. So anyone reading this who thinks it is a good idea, please join me in posting where you find your fake or real questions.

People should include the company as well as the source, since sometimes the quality of questions within a company can even vary greatly depending on the source. For example, one book published by a company could suck while their online content could be wonderful.