GMAT Tip of the Week: No News Is Good News

GMAT Tip of the WeekWe all have a laundry list of answers to the question “what makes Data Sufficiency difficult?” — it’s a unique question type; the math skills involved can be quite tricky; subtle phrasing and precision-in-wording can make huge differences; the situations are often abstract and difficult to conceptualize. But what about a better question – “what makes Data Sufficiency easier?” There are actually quite a few examples of this, and many relate to the Veritas Prep mindset “Think Like the Testmaker”. We can even break it down to one word:

Clues.

In all actuality, business schools don’t much care whether you can list all the factors of 224 or whether you know that the diameter and tangent of a circle are perpendicular at that point of tangency. What they do care about, though, is your ability to see opportunity – or danger – where others do not; your ability to recognize trends and use them to make decisions; your ability to read your opponent, whether a competitor or a negotiator, and come out on top. And so a great many “difficult” Data Sufficiency questions are written so that they embed clues to help astute test-takers – those with the abilities prized by business schools and employers – avoid trap answers and make good decisions.

One such clue comes in the form of what we’ll call “No News is Good News”, meaning that if the two statements in a Data Sufficiency question provide the exact same information:

-The answer can only be D or E (one can’t be sufficient without the other, and if they say the same thing then there’s no benefit to using both together)
-You now have twice as much time to invest in “the work” on one statement, since that work will cover both statements
-You have an opportunity to save yourself from a bad decision

Let’s investigate all three of those points, but particularly the last one, with an example:

All attendees at a university gathering are faculty or alumni of the university. Are any of the attendees both faculty and alumni?

(1) 3/5 of the attendees are members of the university faculty

(2) 40% of the attendees are not members of the university faculty

Now, many test takers (about half in the Veritas Prep Question Bank, as well as a couple of admittedly-distracted VP staffers seeing this question for the first time) will go through the following progression:

1) 3/5 = 60%, so I see what’s going on here…statement 1 says 60% and statement 2 says 40%

2) (and this is incorrect…more on that in a second) Well if 60% are faculty and 40% are “something else”, and there are only faculty and alumni and no one at this event is “neither”, then it looks like it’s 60% faculty and 40% alumni with no overlap, so the answer must be C, both statements together.

Which isn’t horrible logic, even though it’s incorrect. It’s a relatively understandable progression – but here’s where “No News is Good News” can help. If you really think about it, statements 1 and 2 basically say the same thing. If someone were to ask “what percent of people are not faculty” after statement 1, you’d have to say “well if 60% are, then 40% are not”. So if you think about it, statement 2 doesn’t tell you anything new. So how could the answer be C?

This is your clue to go back and re-investigate and save yourself. Statement 2 doesn’t mean “exactly 40% are alumni”, it only means “40% are not faculty”. So those 40% have to be alumni, but alumni isn’t limited to 40%. That 40% is just “alumni who are not faculty”. Consider the hypothetical that, out of 100 attendees, 60 are faculty, 50 are alumni, and 10 are therefore “both”. That’s perfectly consistent with the statements but doesn’t give you the same number for “both” that you would have had had you picked C.

So the answer is E, but the lesson is probably more important – the fact that the two statements gave you the exact same information was your clue that had you initially thought “C” you had to go back and do some work. When the two statements each tell you the same thing, the answer has to be D or E, and usually that means you have to put in a little due diligence to make sure you choose wisely.

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By Brian Galvin

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