Wording and interpretation of statements in DS

[linw1988]

Without going too much into the question, as it was from the Quant Review 2 book (DS #60 if that helps), I have a question about the wording of one of the statements for Data Sufficiency.

The statement says that "the difference between the length and the width ... is X feet." (where X was given in the problem.)

The explanation says that this information tell us that length - width = X, and based on the DS problem, would give one unique number to length and one number answer to width and be sufficient.

My question is, with the way the statement was worded, why can we not assume that w-l = x as well as l-w=x. This would give two sets of lengths and widths and be insufficient.

This is more about the wording seen in data statements and it's not really about the question itself. Please let me know if similar wording is to be assumed in future cases.

Thanks for your time.

[tim]

This is a terribly worded question, and I totally see your point. I suppose the lesson to be learned here is that the GMAT considers "the difference between A and B" to be A-B. It's not like the GMAT to rely on such a subtle linguistic trap that even mathematicians disagree on, so I'm going to run this by the other moderators to see whether there's anything you and I both missed or whether there is any indication that this is a typo.

[RonPurewal]

My understanding is that, when the terms "length" and "width" are used to describe the dimensions of a rectangle, the former refers to whichever dimension is greater, and the latter to whichever is less.
E.g., if you draw a rectangle with 4-foot vertical sides and 6-foot horizontal sides, then the "length of the rectangle" is 6 feet. If the rectangle has 6-foot vertical sides and 4-foot horizontal sides, then the "length of the rectangle" is still 6 feet.

It appears that GMAC is using this definition, too. There aren't any other problems that depend on it (!!), but, if you look at any of the considerable number of problems on which "length" and "width" are used (e.g., OG12 #4, #18, #118), you'll notice that "length" is always used to refer to the longer of the two dimensions. That's probably not a coincidence.

So, two things.

1/
You should know that "length" > "width".

2/
I think it's highly unlikely that any problem on the modern GMAT would depend on this distinction. (That's "highly unlikely" as in "I would bet thousands of dollars on it".)
Remember that the quant and verbal supplements are, in essence, second-rate problems - they are entirely composed of problems that were left out in the transition between the 10th and 11th editions of the OG.
So, some of the problems will have issues that won't show up in more recent OG editions, and/or reflect things that simply aren't tested anymore.
For instance, the verbal supplement has lots of problems that depend on extremely obscure idioms. (E.g., I don't think many people except professional writers would know what you have to know about "excepting" in SC problem #18.) The modern GMAT has more or less entirely disposed of such obscure idioms, and will instead test more common idioms that are just better disguised. But, studying the supplement (= old, superannuated problems), you may come away with the incorrect notion that you still have to pore over lengthy lists of obscure idioms that even native speakers don't know.

What I'm not saying, of course, is that the quant and verbal supplements are useless. They're worse than the main OG and GMATPrep - both of which reflect more recent priorities in their questions, and both of which contain questions that are better edited and presented - but they're still much, much better than random third-party sources.
But, if you doubt something that's in them, just ask about it here!

[tim]

Thanks, Ron! So it looks like we just need to remember this is how the GMAT defines "length".