Critical Reasoning

In a certain wildlife park, park rangers are able to track the movements of many rhinoceroses because those animals wear radio collars. When, as often happens, a collar slips off, it is put back on. Putting a collar on a rhinoceros involves immobilizing the animal by shooting it with a tranquilizer dart. Female rhinoceroses that have been frequently recollared have significant lower fetility rate than uncollared females. Probably, therefore, some subtances in the tranquilizer inhibit fertility.

Inevaluating the argument, it would be most useful to determine which of the following?
a. Whether there are more collared female rhinoceroses than uncollared female rhinoceroses in the park.
b. How the tranquilizer that is used for immobilizing rhinoceroses differs, if at all, from tranquilizers used in working with other large mammals.
c. How often park rangers need to use trangquilizer dart to immobilize rhinoceroses for reasons other than attaching radio collars.
d. Whether male rhinoceroses in the wild park lose their collar any more often than the park's female rhinoceroses do
e. Whether radio collar is the only pratical means that park rangers have for tracking the movements of rhinoceroses in the park.

OA: C

Hello.

I have no doubt about the choice C because it exploits the flaw in the argument.
But I still have a doubt about choice A.
The author makes a comparison between the fertility rates between 2 groups to support his conclusion. If there are 1000 recollared rhinos and 10 uncollared rhinos, and the fertility rates are 50% and 80% respectively, so we have 500 fertile recollared rhinos and 8 fertile uncollared rhinos.

if the difference between numbers of the two groups are too large-- i.e. 1000 and 10 -- and if we accept the author's assumption that the only purpose to shoot rhinos with T darts is to put collar, does the comparison between the fertile rates support the conclusion?

I must ask the question because before I see the correct answer I did not know the flaw of the argument, and the choice A seems good to me. So, if I know the answer for the question, I can eliminate choice A.

Thank you.

The comparison between absolute numbers of fertile females from both groups has no impact whatsoever on the argument. This is because the author's conclusion is about fertility "rates". Knowing that there are 500 fertile females in one group and only 8 in the other gives no information about fertility rates.

If I made an argument that people who drive drunk have much higher rates of accidents per mile driven than people who drive sober, information about the number of people in each group alone doesn't help or hurt my argument in any way.

I cannot understand how the Question relates to the given answer choice. As in, why can't D be a choice since we know that tranquilizers affect both female and male rhinos. So if male rhinos are unaffected in comparable means, then we know its not necessarily the tranquilizer?

Can you please help me understand what we need to look for in this type of question?

Thanks

The initial argument is a correlation. Collared females are less fertile than uncollared females. Collared females are shot with tranquilizers. Therefore, tranquilizers must be affecting the fertility of collared females.

A doesn't matter. The question talks about fertility rate, so raw numbers are irrelevant.

B mentions other large animals, and we're only concerned with rhinos.

C works by giving us more information about potential tranquilizer use in the uncollared female population. If non-collar use is rare, then the tranquilizer might explain the difference in fertility. However, if non-collar use is common, then uncollared females are also being dosed with tranquilizers yet still maintaining a higher fertility rate. This would point to tranquilizers NOT being the cause of the fertility difference.

D is irrelevant to the fertility of female rhinos.

E mentions alternative to radio collars, which isn't directly relevant to the argument (tranquilizer-->lower fertility)

theunheardmelody wrote:I cannot understand how the Question relates to the given answer choice. As in, why can't D be a choice since we know that tranquilizers affect both female and male rhinos. So if male rhinos are unaffected in comparable means, then we know its not necessarily the tranquilizer?

Can you please help me understand what we need to look for in this type of question?

Thanks

In a "useful to evaluate" question like this, they're asking us to figure out what information would allow us to decide how good the argument is.

This means that, as written, the argument is missing something; there's a gap somewhere, and you should try to find it before going to the answer choices.

The correct answer is the one that resolves the gap that you noticed. The info given is usually vague, and you typically won't know if the actual numbers will help or hurt the argument, but you'll know that bringing in the additional info will allow you to say "yes, good argument" or "no, bad argument."