Let's break this problem down. Some explanations in this forum focus exclusively on how to answer specific, isolated questions. But remember: the GMAT is a critical-thinking test. For those of you studying for the GMAT, you will want to internalize strategies that help you to identify and solve entire classes of questions. Pattern recognition is key. The tactics I will show you here will be useful for numerous questions, not just this one. This solution is going to walk through not just what the answer is, but how to strategically think about it. Here is the full "GMAT Jujitsu" for this question:
This question is clearly a "
Strengthen" question, given the question stem. With strengthen questions, your job is to identify the conclusion and then look for the logical gap between the conclusion and the facts upon which that question relies. The conclusion is also clearly identified with the leverage word "
Therefore..." (see the last sentence.) The overarching structure of the argument is simple: reinfection happens with a "seven-day" antibiotic because many people stop after three days of taking that drug. A new antibiotic is a "three-day" antibiotic. Therefore (in theory), reinfection will occur less often if patients use the antibiotic with the shorter prescribed course. However, you might wonder: just because people stop taking penicillin or erythromycin after three days (four days shorter than they should, resulting in reinfection), this doesn't prove that people will take the new antibiotic for three days. We make an unjustified assumption (an "
Overgeneralization") when we think that people will use one drug in the same way that they would use another drug.
We need to find the answer that explains why someone will take the "three-day" antibiotic for its fully-prescribed period, while people seem to ignore the "fully-prescribed" period for penicillin or erythromycin. Any answer that doesn't help us repair this logical gap can't be the right answer. Let's look at each answer:
Quote:
A. Some of the people who are allergic to penicillin are likely to be allergic to the new antibiotic.
Some people argue that "
A" is outside the scope of the argument, but it isn't necessarily. Think about it... being allergic to a drug could be a
good reason why you stop taking a drug early. And yet, in order for this answer to work, we have to insert a major, unjustified assumption: that people allergic to either drug still continue to take the drug for three days, regardless of the reaction (thus completing the prescribed course of one drug, while not completing the prescribed course of another.) There is no evidence of this, so we can look for a stronger answer.
Quote:
B. A course of treatment with the new antibiotic costs about the same as a course of treatment with either penicillin or erythromycin.
If the costs are the same for an entire "
course of treatment", then there is no explicit reason why someone would stop early. This doesn't focus on the logical gap.
Quote:
C. The new antibiotic has been shown to be effective in eradicating bacterial infections other than strep.
This answer is truly outside the scope of the argument. The argument talks specifically about the "
treatment of strep infections", so this answer is baiting you into focusing on something outside of the argument. Anything that doesn't "
mind the gap" in the logic is a distracting detour. It doesn't matter whether the new antibiotic cures anything else, tastes like gummy bears, or is recommended by 9/10 dentists. If the answer doesn't explain why a three-day regimen is better at reducing reinfection rates for
strep infections, it is irrelevant. I call these type of trap answers "
Distracting Detours" in my classes.
Quote:
D. Some physicians have already begun to prescribe the new antibiotic instead of penicillin or erythromycin for the treatment of some strep infections.
Answer choice "
D" contains a trap similar to the issue in "
C". Just because some physicians have prescribed the new antibiotic doesn't mean that it is better at reducing reinfection rates. This question is a classic "expert trap", where an answer choice defers to expert opinion without saying why the experts did what they did.
Quote:
E. Regardless of whether they take a traditional antibiotic or the new one, most patients feel fully recovered after taking the drug for three days.
"
E" gives a reason for why people stop taking the drug after three days: they "
feel" better. "Feeling" better doesn't mean they are not at a risk of reinfection, nor is it equivalent with "cured." On the GMAT, it is dangerous to conflate terms that aren't truly synonymous. Someone can have reduced symptoms and still be prone to reinfection. The problem clearly states that reinfection is common because "
many people stop taking those drugs" early. And "
E" gives a reason for why people stop after three days. For penicillin or erythromycin, three days is insufficient. For the new antibiotic, three days is recommended. Answer choice "
E" is the best answer.
However, "
E" is not a perfect answer. It is still
possible that the new antibiotic is not as effective or could have a higher rate of reinfection, even after the entire prescribed course is taken. But we don't need to find the answer that perfectly plugs every logical hole. We just need the one that "
minds the gap" the best. Just look at the way the question is worded: it asks for an answer that "
most strengthens" the argument. Four of our answer choices either are irrelevant, bait you into thinking about criteria outside of the argument, or require major additional assumptions to make work. In other words, they don't focus on fixing the logical gap. Answer choice "
E" is the only one that nudges us in the right direction. I like to call these type of answer choices "
Directional Nudges" in my classes. We see this pattern pretty often on the GMAT.
close
27 Apr 2008, 11:51
45%
(medium)
35%
(01:54)
wrong 
