Logical reasoning PrepTest 110 · Section 3 · Question 11

Incorrect. Since people are living longer, the proportion of the population with these disorders can increase even if they don't strike younger people—they just have to strike a significant proportion of older people who could, as people live longer, make up a larger proportion of the population.

Incorrect. Even if people do live long enough to need a second transplant, they could still receive that transplant and thus be more likely to develop a brain disorder instead of dying to a disease of that other organ. This answer is thus not necessary for the argument to work.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
Medicine can transplant most organs, but it's impossible to do a brain transplant. So as organ transplantation continues to get better, a higher proportion of the population will have brain diseases.

Answer Anticipation:
The argument here—including the conclusion—very much trades in comparisons between brain diseases and transplants, and other organ diseases/transplants.

On the transplant front, we learn that organ transplants are increasingly common and successful, whereas brain transplants "can never" be done. So while say heart disease can be cured with a heart transplant brain disorders won't be similarly curable.

Moving to the conclusion it states that the population with brain disorders will take up an "ever—increasing" proportion. Why is that? Well to make sense more people would need to have brain disorders while fewer people would need to have other disorders or die from those disorders. How does that make sense in the context of the premises? If the other diseases are cured while the brain disorders aren't.

While the premises do establish that other diseases can be cured by transplants and brain diseases can't there's no indication that these brain diseases won't be curable through other means. And if that's the case then people suffering from them might not make up a growing proportion of the population. Let's find an answer ruling out that possibility.

Answer Explanation:
This answer addresses the other ways that brain disorders might be cured. While transplants can't be used to address these disorders if other cures are possible then there's no guarantee that more and more people will have the disorders. The argument assumes these other treatments don't exist and thus this is the correct answer.

Key Takeaway:
Comparative language in a conclusion demonstrates that the argument is either based on comparative logic or it is assuming something about a comparison. Always note such language when it shows up in a conclusion and analyze the premises to see if it's supported.

Incorrect. What matters is whether the proportion can grow, and a small or a large current proportion could get bigger. Also, while deaths are related to the conclusion (after all, if you die, you no longer are living with a degenerative brain disorder), the death rate only matters inasmuch as it determines the population suffering from the disorder. As such, even if brain disorders currently account for a larger proportion of deaths, the proportion living with such a disorder can still grow.

Incorrect. If anything, this answer would suggest that other treatments are being developed through this research money, which cuts against the argument. That said, money spent on research doesn't guarantee anything will come of it, so this answer really doesn't affect the argument at all.