PrepTest 152

Incorrect. The argument doesn't rely on level of demand being the only factor—it could just be, by far, the most important one, and the argument would still work.

Incorrect. The argument does rely on information from junkyards to reach the conclusion, but it doesn't rely on all cars of that age being sold to junkyards. Even if some cars of that age are sold through other channels, as long as what happens as junkyards is representative of demand overall, the argument could still work.

Incorrect. Two issues here. First, the argument only requires a split for the cars and parts at the 10 year mark, not a spectrum across all ages and difficulties. Second, the rule would only need to apply to cars, not to all things.

Incorrect. The stimulus doesn't establish that there's a lack of demand for cars less than ten years old—if anything, the argument says that there is a demand for them for parts.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
The more demand, the easier to sell. Junkyards will buy cars under 10 because the parts are easy to sell, but not cars 10 and older because the parts aren't easy to sell. Therefore, under-10 used cars are easier to sell than 10+ used cars.

Answer Anticipation:
The argument here establishes a general principle—selling something is easier when there's more demand for it. It then talks about the ease of selling car parts in order to draw a conclusion about the demand for the cars themselves. While demand for car parts is part of the market for a given set of cars, there's no indication that it's a significant portion, let alone a representative portion or a determinative portion. This argument relies on demand for parts being related to overall demand for cars of a certain age, so the correct answer will need to connect those ideas.

Answer Explanation:
This answer choice connects the salability of parts to the salability of the cars themselves. If the salability of cars is not largely a function of the demand for their parts, then the information about selling cars to junkyards for parts doesn't speak to the overall demand for the cars. Note that even though this answer only connects these ideas for the older cars, that's not a problem for the answer. For the argument to work, this relationship has to hold for both older and newer cars, so it has to hold for older cars, as this answer says.

Key Takeaway:
Remember that Strengthen with Necessary Premise questions aren't Strengthen with Sufficient Premise questions. Here, seeing that answer (E) only talks about the older cars might lead you to eliminate it. However, the relationship we were looking for has to exist for both sets of cars, so it has to exist for each of them individually. The correct answer in this question type won't necessarily justify the conclusion, so don't rule out an answer because it doesn't.