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by ankitongmat » Sat Oct 27, 2012 4:34 am
Outbreaks of Rift Valley fever occur irregularly in East Africa, several years apart. When
outbreaks do occur, they kill thousands of cattle. A livestock vaccine against the disease
exists but is rarely used. It is too expensive for farmers to use routinely, and since it is not
effective until a month after vaccination, administering it after an outbreak begins helps
very little. Nevertheless, experts predict that use of the vaccine will increase significantly
within the next few years. Which of the following, if true, provides the strongest
justification for the experts' prediction?
A. Rift Valley fever is spread by mosquitoes, but each outbreak is so widespread that it is
impractical to control it by using insecticides.
B. When an outbreak of Rift Valley fever occurs, unaffected countries often refuse to import
livestock from the countries affected by the outbreak.
C. It would take less than a month for producers of the vaccine to adjust their production
operations to cope with a large increase in demand.
D. Many cattle farmers in East Africa are nomadic or live in remote villages, and such farmers,
who have little access to modern veterinary medicine, are particularly hard hit by outbreaks
of Rift Valley fever.
E. Recently published research has shown that certain identifiable climatic conditions are
almost invariably followed, within two to five months, by an outbreak of Rift Valley fever.

Why the answer not A and why it is E? Can someone plz help
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by bursal » Fri Nov 30, 2012 5:35 pm
The key here is to focus on the apparent paradox between what has been the case to date (the vaccine is rarely used) and what is predicted for the future (the use of the vaccine will increase significantly). What would need to change for this prediction to come true?

Well, the reason for the current low usage of the vaccine is twofold, as we are told: First, the vaccine is too expensive to be used regularly, and second, once an outbreak actually starts, it is too late for the vaccine to be effective. Think about it: if you used the vaccine regularly, you might avoid the outbreak, but it would cost you too much.

But what if you could predict an outbreak before it actually happened? In that case, you could use the vaccine right before the outbreak and protect yourself, without having to incur the cost of regular use. That is what the correct answer, E, offers. Meanwhile, A has at least two problems with it. First and foremost, it misses the mark by not addressing the two valid reasons for NOT using the vaccine. Also (more subtly), by introducing the idea of insecticides as an alternative to the vaccine, it actually sets the stage for a potential weakening of the argument, in the sense that there might be another means of combatting the outbreak besides the vaccine.
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by GMATGuruNY » Sun Dec 02, 2012 5:22 am
ankitongmat wrote:Outbreaks of Rift Valley fever occur irregularly in East Africa, several years apart. When
outbreaks do occur, they kill thousands of cattle. A livestock vaccine against the disease
exists but is rarely used. It is too expensive for farmers to use routinely, and since it is not
effective until a month after vaccination, administering it after an outbreak begins helps
very little. Nevertheless, experts predict that use of the vaccine will increase significantly
within the next few years. Which of the following, if true, provides the strongest
justification for the experts' prediction?
A. Rift Valley fever is spread by mosquitoes, but each outbreak is so widespread that it is
impractical to control it by using insecticides.
B. When an outbreak of Rift Valley fever occurs, unaffected countries often refuse to import
livestock from the countries affected by the outbreak.
C. It would take less than a month for producers of the vaccine to adjust their production
operations to cope with a large increase in demand.
D. Many cattle farmers in East Africa are nomadic or live in remote villages, and such farmers,
who have little access to modern veterinary medicine, are particularly hard hit by outbreaks
of Rift Valley fever.
E. Recently published research has shown that certain identifiable climatic conditions are
almost invariably followed, within two to five months, by an outbreak of Rift Valley fever.

Why the answer not A and why it is E? Can someone plz help
FACT 1: The vaccine is too expensive for farmers to use routinely, and since it is not effective until a month after vaccination, administering it after an outbreak begins helps very little.
FACT 2: Experts predict that use of the vaccine will increase significantly within the next few years.

The correct answer must explain how both facts can be true at the same time.

Answer choice E: Recently published research has shown that certain identifiable climatic conditions are almost invariably followed, within two to five months, by an outbreak of Rift Valley fever.
Thus, the time needed for the vaccine to begin working is not an issue: the vaccine can be administered when certain identifiable climactic conditions are seen, giving the vaccine sufficient time to begin working and prevent an outbreak of Rift Valley Fever.

The correct answer is E.

Answer choice A: Rift Valley fever is spread by mosquitoes, but each outbreak is so widespread that it is impractical to control it by using insecticides.
This answer choice does not explain why the time needed for the vaccine to begin working will not render the vaccine ineffective.
Eliminate A.
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by tanviet » Tue Dec 04, 2012 2:32 am
Thank you Hunt.

I find this question hard.

I consider this question the strengthening one. and to do a strengthening, I first I prethink an assumption, then I prethink a strengthener.

- conclusion: the use will incrases.
- prethink an assumption: there is no bad agent happening

- go to answer choice, find the thing which help prevent the bad thing and support the belief that the use will increase.

I can not find choice E.

So, my process dose not work for this question.

I can not prethink as expert Hunt and fail. I realize that what we do before going to answer choices is fatally important to realize the correct answer. I can not prethink as expert Hunt

we need to prethink the rather specific thing which we will find in the answer choices. if we do this prethinking wrongly, we fail.

I made a test to show that the prethinking is fatally important. I read only the prethinking process of expert Hunt and stop reading and return to the answer choices to do by myself. in this case, I feel good and realize the correct answer.

so, the question is how to prethink correctly to be succussful. ?

pls help, comment.
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