Consulting firm

Problem Solving — algebra and arithmetic (GMAT Focus Edition)
This topic has expert replies
Newbie | Next Rank: 10 Posts
Posts: 4
Joined: Tue Oct 12, 2010 10:47 am
Location: chicago,il
GMAT Score:640

Consulting firm

by suri84 » Thu Nov 04, 2010 12:06 pm
1.The president of a consulting firm analyzed the decisions made about marketing by her clients and concluded that the decisions were correct only about half of the time.
The conclusion above depends on the presupposition that
(A) companies can be successful even when about half of the decisions they make about marketing prove to be wrong
(B) companies hiring her consulting firm make no more incorrect marketing decisions than do companies in general
(C) executives consistently making correct marketing decisions rarely enlist the aid of a consulting firm
(D) marketing decision are just as likely to be correct as they are to be incorrect
(E) it is possible to classify a marketing decision properly as being either right or wrong

I am confused between options D and E

Kindly post your explanations.
Source: — Quantitative Reasoning |

User avatar
GMAT Instructor
Posts: 1031
Joined: Thu Jul 03, 2008 1:23 pm
Location: Malibu, CA
Thanked: 716 times
Followed by:255 members
GMAT Score:750

by Brian@VeritasPrep » Fri Nov 05, 2010 11:51 am
Hey suri84:

Good question - and for questions like these that ask for an assumption or presupposition upon which the argument depends, it's often helpful to consider the impact of the OPPOSITE of the answer choices. After all, if the argument depends on that statement, then the opposite of that statement should attack the argument.

With answer choice E, the correct answer, the opposite is:

It is NOT possible to classify a marketing decision properly as right or wrong

In this case, she then doesn't have a point at all - she cannot conclude that "half of the decisions were correct" because there is simply no way to know whether the decision was correct or incorrect. Because the opposite of the statement directly attacks her argument (and basically ruins it), then we can tell that the statement itself is necessary.


Choice D, when negated, is:

Marketing decisions are NOT just as likely to be correct/incorrect

Here this opposite would actually strengthen her argument somewhat, as her point is that the decisions were "only" right 50% of the time as though that was surprising. In either case, though, the general statistic of how often decisions are right/wrong isn't really applicable here - the conclusion is specific to her particular clients and their decisions. So whether the typical ratio is 50-50 or 20-80, neither would change the fact that her particular hit rate is 50-50. That's why D is irrelevant, and E is the correct answer.
Brian Galvin
GMAT Instructor
Chief Academic Officer
Veritas Prep

Looking for GMAT practice questions? Try out the Veritas Prep Question Bank. Learn More.