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This page shows a recording of a live class. We're working hard to create our standard, concise explanation videos for the questions in this PrepTest. Thank you for your patience!

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This page shows a recording of a live class. We're working hard to create our standard, concise explanation videos for the questions in this PrepTest. Thank you for your patience!

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This page shows a recording of a live class. We're working hard to create our standard, concise explanation videos for the questions in this PrepTest. Thank you for your patience!

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Many people joke about Friday the thirteenth being an unlucky day, but a study showed that in one year approximately 17 percent of people scheduled to fly canceled or did not show up for their flights on Friday the thirteenth—a rate higher than that on any other day and date in that year. This shows that a significant percentage of the population would rather disrupt their travel plans than risk flying on a supposedly unlucky day.

Summarize Argument: Phenomenon-Hypothesis

The author hypothesizes that a significant proportion of the population are willing to disrupt their plans to avoid flying on an “unlucky” Friday the thirteenth. This hypothesis is based on the observation that during a particular year, more people cancelled or didn’t show up to their flights on Friday the thirteenth than on any other day that year.

Notable Assumptions

The author assumes that the reason people didn’t show up for their flights on Friday the thirteenth was the unlucky date, and not some other reason. There aren’t that many Fridays the thirteenth in a single year, so maybe some other significant factor just happened to arise on one or more Fridays the thirteenth that year.

A
People who fly tend to be professionals who as a group are less superstitious than the general public.

Even if people who fly are less superstitious, that doesn’t mean they’re not superstitious—maybe an even higher percentage of the general public would have skipped their flights. This doesn’t provide an alternative explanation, or make the author’s explanation any less likely.

B
Surveys show that less than 5 percent of the population report that they believe that Friday the thirteenth is an unlucky day.

This just doesn’t give us enough context to know how it relates to the 17 percent of people who missed their flights on Friday the thirteenth. Maybe only a very tiny percentage of people fly, and they’re unusually likely to be superstitious—we don’t know.

C
Weather conditions at several major airports were severe on the Fridays that fell on the thirteenth in the year of the study.

This weakens by providing an alternative explanation for why more people missed their flights on Friday the thirteenth. If there happened to be severe weather those days, it makes sense that people would miss their flights even without superstition being involved.

D
In the year of the study, automobile traffic was no lighter on Friday the thirteenth than on other Fridays.

This does not weaken, because the domain of the argument is specific to flights. It would be perfectly reasonable for people to fear flying on an unlucky day but not fear driving, because driving is a much more routine activity.

E
The absentee rate among airline workers was not significantly higher than normal on the Fridays that fell on the thirteenth in the year of the study.

This does not weaken, because there are other factors that explain why airline workers might show up to work on an “unlucky” day. So this doesn’t really contradict the observed data about passengers, and still doesn’t explain the phenomenon.


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This is a strengthening question, indicated by: Which one of the following, if true, most strengthens the argument?

Our argument claims that if a library shared by two towns was moved from a smaller building in the lower population town to a larger building in the higher population town, that the library would be within walking distance of the library. It is worth noting that we have a conditional conclusion; if we move the library, then it will have more users within walking distance. It is important to remember that the truth of a conditional statement is independent from the truth of either of its conditions. For example, the statement “if it rains then the sidewalk will be wet” could be true even if it never rained and the sidewalk was never wet; the truth of a conditional is about the relationship between the two conditions, more specifically, whether the sufficient term is enough for the necessary term to be true.

Now when judging an argument with a conditional conclusion, we can either keep this in mind, or kick up the sufficient condition by making it a premise. In this case, we would simply add that the public library will be relocated, and now the conclusion we want to strengthen is that there will be more users within walking distance. The problem we should recognize with this argument is that we have a term shift; our support is about the total population of the two towns, but our conclusion is about specifically library users and even more specifically those within walking distance. It could be true that there are more people living in central Glenwood than central Redville, and yet there could be less library users, or the city could be less dense so that there are actually less people in general within walking distance. An answer choice which filled this gap between our support and our conclusion would be a great strengthening answer. Let’s see what we get:

Answer Choice (A) For all we know the old area between the two towns had more people within walking distance! Just because it was between the two cities we can’t assume there weren’t lots of people living nearby.

Correct Answer Choice (B) This helps fills our gap; now that we know that the cities are of comparable size, if one has a larger total population then it will have a greater population density, which would support that more people would be in walking distance of the new location.

Answer Choice (C) Our conclusion is about the number of library users in walking distance; the size of the building itself has no obvious impact on that factor.

Answer Choice (D) We don’t care about these out-of-city people; our conclusion is about a difference in the number of walking distance library users, who would all be within the city.

Answer Choice (E) The key words here are currently and considered. We aren’t interested in what people consider walking distance, we want to know how many library users are in actual walking distance. If the people are currently walking to the library, then regardless of what people consider they are by definition within walking distance. So all this answer really tells us is that people do walk to the current library location; this doesn’t give us any info to support that the new location will be better.


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This page shows a recording of a live class. We're working hard to create our standard, concise explanation videos for the questions in this PrepTest. Thank you for your patience!

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