LSAT 109 | Section 3 | Logical Reasoning: Q5

LR Question 5 Explanation

QUESTION TEXT: The radiation absorbed by someone during an ordinary…

QUESTION TYPE: Flawed Reasoning

CONCLUSION: Airline flight crews aren’t at risk from airplane radiation.

REASONING: The radiation received on a single flight is no more than you receive during a dental X-ray. And a dental X-ray isn’t harmful.

ANALYSIS: The stimulus gives us good evidence that one flight isn’t dangerous. But airplane crew are on many flights. They might be at risk from the repeat exposure to radiation.

This question offers a good example of how to use the narrow focus of the conclusion to eliminate wrong answers. The conclusion is only about airplane radiation risk to flight crew. A and C talk about non-airplane radiation. E talks about other risks. B talks about the benefits of dental X-rays.

___________

1. Of course there are other kinds of dangerous radiation: you wouldn’t want to stand in a nuclear reactor core. But non-airplane types of radiation don’t change the radiation risk faced by airline crew. 
2. This shows a benefit from a dental X-ray. But the main point was that the X-ray also wasn’t harmful. 
3. Same as A. An airplane only poses a dental X-ray level of radiation risk. So it’s relevant to compare an airplane to an X-ray and irrelevant to compare it to worse sources of radiation. 
4. CORRECT. Airline crew are exposed for longer and more often than most people. So they may face an increased risk even if a single flight is safe on its own. 
5. Sure, the plane could crash. But the conclusion is specifically about radiation risk.