PrepTest 113

Incorrect. The argument is about the relative likelihood, so there's no assumption that any subset of cars is likely to get into an accident. Cars without air bags having a 3% accident rate and cars with having a 7% aligns with the argument.

Incorrect. The conclusion is that cars with air bags are "no safer than" cars without. That leaves open the possibility that cars without air bags are safer than cars without—if they're safer than those with air bags, then cars with air bags are no safer than the others. As such, it doesn't deny that possibility.

Incorrect. This possibility doesn't create issues for the argument, as it doesn't contradict the higher accident rate for cars with air bags. As long as the totality of accidents shows that cars with air bags get in accidents more frequently than those without, it's possible for some accidents to essentially be a wash.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
Cars with air bags vs. Cars without air bags
(1) With - Greatly reduced risk of serious injury when in an accident
(2) Without - Less likely to be in an accident in the first place
Conclusion - Cars with air bags aren't safer than cars without

Answer Anticipation:
This argument relies heavily on the comparison between cars with and without air bags in their risk of getting into an accident, and their risk of serious injury in an accident.

The two metrics cut different ways. Cars without air bags are safer in that they are less likely to get into accidents. However, cars with air bags are much less likely to result in serious injury once in an accident.

The conclusion takes these two points and says that cars with air bags are "no safer" than the ones without them. However, in reaching the conclusion that the safety is similar, it's assuming that the factors brought up are essentially equivalent—that the risk of getting into an accident is as important to overall safety as the risk of serious injury once in the accident. It's possible that one of those is more important than the other, so we should look for an answer discussing this assumption.

Answer Explanation:
This answer addresses the assumption we identified in the stimulus. While risk of getting into an accident and risk of serious injury when in an accident are both relevant to overall safety, we don't know which is more important, and the argument doesn't establish that neither are. However, it assumes that they're equivalently related (or that risk of getting in an accident is more important, thus making cars without air bags safer), so this answer is correct.

Key Takeaway:
When arguments are based on comparisons, the correct answer will usually play into that comparison, so make sure you understand all aspects of it and where the shortcomings/assumptions are.

Incorrect. The air bags just need to deploy enough to lower the risk of serious injury for the argument to work, so the argument doesn't take for granted that they always deploy.