gmatprep09 wrote:
If retail stores experience a decrease in revenues during this holiday season, then either attitudes toward extravagant gift-giving have changed or prices have risen beyond the level most people can afford. If attitudes have changed, then we all have something to celebrate this season. If prices have risen beyond the level most people can afford, then it must be that salaries have not kept pace with rising prices during the past year.
Assume the premises above to be true. If salaries have kept pace with rising prices during the past year, which one of the following must be true?
(A) Attitudes toward extravagant gift-giving have changed.
(B) Retail stores will not experience a decrease in retail sales during this holiday season.
(C) Prices in retail stores have not risen beyond the level that most people can afford during this holiday season.
(D) Attitudes toward extravagant gift-giving have not changed, and stores will not experience a decrease in revenues during this holiday season.
(E) Either attitudes toward extravagant gift-giving have changed or prices have risen beyond the level that most people can afford during this holiday season.
In general, the Analytical Reasoning questions from the LSAT are slightly more challenging versions of the GMAT CR questions, and therefore make good practice for GMAT students who want to challenge themselves. This particular question relies a bit too heavily on formal logic --- that's fine for the LSAT, but GMAT students need not wrestle with this much formal logic.
This argument has the following formal design.
First sentence = If M, then N or P
Second sentence = If P, then not Q.
Here,
M = retail stores experience a decrease in revenues during this holiday season
N = attitudes toward extravagant gift-giving have changed
P = prices have risen beyond the level most people can afford
Q = salaries have kept pace with rising prices during the past year
The question stem tells us ---- assume Q. With this, we can use a variant of a classical argument type known as
Modus Tollens.
MODUS TOLLENS: Given (
If W, then Y) and (
not Y), we can conclude (
not W).
The argument gives us "If P, then not Q", and the question stem gives us Q, so according to
Modus Tollens, we can conclude "not P" --- i.e. "
Prices in retail stores have not risen beyond the level that most people can afford during this holiday season." This is precisely what
(C) says.
Because we know nothing about the truth or falsehood of M, we can draw no conclusion about N. If we were given both "not P" and M, we could conclude N, but in the absence of information about M, we can conclude nothing about N.
Everything I have said here is well beyond what anyone needs to know for the GMAT. If love this stuff, then forget business school --- take the LSAT and become a lawyer. If you are set on the GMAT and business school, then the last thing you need to know is
Modus Tollens.
Please let me know if anyone reading this has any questions.
Mike
_________________
Mike McGarry
Magoosh Test PrepEducation is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)