Awaiting the OA. It's definitely between D and E.

For every 40 cats that contract a particular ear infection, one will die from it. Scientists have discovered a vaccine that is almost 100 percent effective in preventing this infection. As the risk of death from complications of vaccination is only one death per 1000 vaccinations, it is, therefore, safer for a cat to receive the vaccine than not to receive it.

Which one of the following would it be most helpful to know in order to evaluate the argument?

A. The total number of cats that die each year from all causes taken together -We are not worried about the number of cats that would die. We are worried about the effectiveness of vaccine.
B. Whether the vaccine is effective against the infection in household pets other than cats -We are not worried about the different types of pets that might benefit from the vaccine. The argument at hand is concerned about the cats.
C. The number of cats that die each year from infections other than the infection in question -We are not worried about the cats that might die from infections other than the one discussed in the argument. We need to evaluate the effectiveness of the vaccine.
D. The likelihood that a cat will contract another infection such as fungal rash -Correct. Because of vaccine if the cats develop another infection, then there is no use of vaccination.
E. The number of cats that will contract the infection in a year. -This option doesn't talk about the effectiveness of the vaccine.

Although I chose E, I argue that the answer is poorly phrased.

We are interested in the likelihood/probability of a cat contracting the ear infection. The number of cats does not give us any information, unless we know the total population of cats.

In my opinion the answer is E
If the number of cats that will contract the infection is known then we can determine that whether to go for vaccinations .
Suppose the number of cats is 100 we know 2 cats will die .
But if the number of cats is 10000 then there will be more cats that will die so vaccinations ia required .
D is just information it does not relate to the argument and it is not mention that new infection developed because of the vaccination

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Although I fell for D, I later realized that E makes sense.

If the no. of cats that contract the infection is significantly less than the total, chances are that more cats might be killed due to vaccination.
If the no. of cars that contract the infection is significantly closer to total, then vaccination is a good idea.

I too second the thought that option is poorly phrased. It should have included the total as well.

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I go for D.

In E, even we know the number of infected cats, there is no use in it.
For example, if there are 1000 infected cats. Number of cats die is 1000/40 = 25.
After vaccination, one in 1000 will die. This is already stated in passage. It shows that number of cats dies will reduce, but doesn't give information that it is safer.

In D, We know that one in 1000 will die. If we even know the likelihood of cats contract another infection after vaccination, we can conclude that it is safe to use.

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The answer is E. Let me tell you why.

Premise 1: For every 40 cats that contract a particular ear infection, one will die from it.
Premise 2: Scientists have discovered a vaccine that is almost 100 percent effective in preventing this infection.
Conclusion: As the risk of death from complications of vaccination is only one death per 1000 vaccinations, it is, therefore, safer for a cat to receive the vaccine than not to receive it.

Understanding: 1 in 40 cats die if they have this PARTICULAR infection. There is a vaccine for this. 1 in 1000 will die if the cats are given the vaccine. Therefore, SAFER to receive the vaccine than not to receive it. Focus on particular. What if the chances of 40 cats having this particular infection is 1 in a million? Vaccinating every cat and causing 1 in every 1000 to die is kind of morbid.

Which one of the following would it be most helpful to know in order to evaluate the argument?

A. The total number of cats that die each year from all causes taken together - Incorrect. Focus is on this particular infection. Anything else is out of scope.
B. Whether the vaccine is effective against the infection in household pets other than cats - Incorrect. Pets are not even discussed in the stimulus, so, discussing household pets and the effect of this vaccine on them irrelevant.
C. The number of cats that die each year from infections other than the infection in question - Irrelevant. We only care about the particular infection and its vaccine.
D. The likelihood that a cat will contract another infection such as fungal rash - Incorrect. Extremely irrelevant. Fungal rash? Outlandish.
E. The number of cats that will contract the infection in a year. - Correct. Due to reason mentioned above.

E because calculation of base rate requires this info.

As per my understanding the author has assumed that in a year their will be atleast 1000 incident because of this infection in cat so he concluded on the basis of this that the probablity of death in 1000 will be less than in 40 so it is safer for a cat to get vaccinated

As we know that in argument evaluation question we have to consider that option which both strenghten and weaken the argument or conclusion
if their are 1000 incident in a year and all of the cat get vaccinated then its strenghten the conclusion
if their are 100 incident in a year then the author don't have the answer on the effectiveness of the vaccine so weaken

Ans E

VeritasKarishma GMATNinja egmat - I have a question with option E-
If number of cats that will contract the infections is more than it make sense to give vaccine
But if number of cats that will contract the infections is less than it also make sense to
vaccine them
For example- if number of cats are only 120 then out of 120, 3 cats will die of infection.
if number of cats are only 120 then out of 120, 1 or 0 cats will die when vaccine is provided

Hi Expert,

Greetings of the day and hope you are doing well.

I would be grateful to you if you assist me with this question as I am unable to apply the extreme technique on this question. I would request you to confirm me whether we can apply extreme technique on the aforesaid question. If not, then, is there any other technique to solve the evaluate question.

Looking for your prompt response ahead.

Can you please explain why is the answer option 'E', thanks

I think the most clear differentiator is the fact that all other choices dont effect the relation between "number of deaths among infected cats" and "no of deaths among cats that will be vaccinated"