Logical reasoning PrepTest 109 · Section 3 · Question 5

Incorrect. Since this argument is designed to compare the two specific forms (X—rays, flight radiation), other forms of dangerous radiation are out of scope.

Incorrect. While this answer does highlight a difference between X—rays and flying, it's not a relevant one to the determination of whether the radiation exposure does harm. Even if dental X—rays prevent tooth decay while flying doesn't improve health, the radiation could still have varying health impacts.

Incorrect. The stimulus notes that the radiation exposure while flying and receiving dental X—rays is equivalently dangerous (or, at least, the former is no more dangerous than the latter), so the flight radiation can't fall into this category of higher—intensity and thus harmful radiation, and this answer is out of scope.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
The radiation during a flight is equivalently dangerous to that of a dental X—ray. The latter does negligible harm, so flight crews face negligible harm from flight radiation.

Answer Anticipation:
The argument relies on similarities between radiation exposure during commercial airline flights and dental X—rays to reach the conclusion that, since the latter don't harm people, the former won't harm flight crews. While several similarities between the two forms of radiation are brought up, and they do relate to harm, other relevant differences with respect to harm could potentially highlight a shortcoming in this argument. Since the question stem is framed as asking us to look for something the argument fails to consider, an answer stating one of these relevant differences would address it.

And one should jump out—frequency of exposure. People receive dental X—rays once every six month (you are up—to—date on your cleanings, right?). Flight crews presumably fly on most days. Let's head to the answers and look for any relevant difference, while expecting this specific one.

Answer Explanation:
This answer brings up a relationship that plays into a relevant difference in the situations. Those receiving dental X—rays do so only infrequently, whereas flight crews are constantly flying. This answer raises the possibility that the longer and more frequent exposure of the flight crews could result in harm, even if a single X—ray and flight aren't harmful.

Key Takeaway:
Arguments that rely on similarities are generally flawed in that they don't consider all relevant factors—including potentially relevant differences. As such, start to think about how the situations may be different in a way that would lead to the conclusion falling apart.

Incorrect. The conclusion is about the harm done by radiation absorption, so this answer is out of scope.