Summarize Argument
The author concludes that this year’s cleanup will be a success. This is based on the fact that if we get at least 100 participants, then the cleanup will be a success. In addition, this year, 85 residents signed up to participate. Last year, only 77 signed up to participate, but over 100 actually participated.
Identify and Describe Flaw
The author assumes that, since last year’s actual turnout was higher than the number who signed up, this year’s actual turnout will also be higher than the number who signed up. This overlooks the possibility that what happened last year won’t happen this year.
A
generalizes about the outcome of an event based on a single observation of a similar situation
The premises describe a single observation of a similar situation (last year’s turnout exceeded the # who signed up). But this doesn’t prove anything about the turnout this year.
B
takes for granted that people who participated in last year’s cleanup will participate this year
The author doesn’t assume that the same people will participate. The argument is just about the number of people who will participate; those people can be different from participants in the past.
C
confuses a condition that is required for an outcome with one that is sufficient for that outcome
There is no condition required for an outcome. We do have a premise telling us that having at least 100 participants is sufficient for the outcome of success. The author doesn’t think having at least 100 participants is necessary for success.
D
overlooks the possibility that the cleanup will attract participants who are not residents in the community
This possibility doesn’t weaken the argument. The cleanup will be a success if it gets at least 100 participants. We have no reason to think where those participants live has any impact on the reasoning.
E
defines a term in such a way as to ensure that whatever the outcome, it will be considered a positive outcome
The author doesn’t define any terms. The author uses a conditional that establishes if we get at least 100 participants, the cleanup will be a success. This is not a “definition” of success. Also, the author doesn’t assume the outcome of the cleanup must be positive.
Summarize Argument: Phenomenon-Hypothesis
The author concludes that car accidents involving teenagers driving to school could be reduced if the school day began later than 8am. This is based on the fact that teenagers tend to be sleepy if they wake up before 8am, and sleepiness can impair driving ability. In addition, when the Granville school’s schedule was changed to begin at 8:30am, the number of car accidents involving teenage drivers in Granville declined.
Notable Assumptions
The author assumes that Granville’s schedule change was the cause of the decrease in car accidents involving teenage drivers in Granville. The author also assumes that there wouldn’t be any effects of a later school start that might tend to increase the number of car accidents involving teenagers.
A
Teenagers start releasing melatonin later at night and stop releasing it later in the morning than do young children.
A comparison to young children has no clear impact. The argument concerns teenagers and is based on statistics concerning Granville’s high school. What children have to do with this statistic or the argument is unclear.
B
Sleepy teenagers are tardy for school more frequently than teenagers who are well rested when the school day begins.
Tardiness has no clear impact on whether starting the school day later can reduce the number of accidents involving teenagers. Whether teens become more or less tardy after the change doesn’t affect accident rates.
C
Teenagers who work at jobs during the day spend more time driving than do teenagers who attend high school during the day.
The argument concerns accidents involving teenagers driving to school and whether this can be reduced by having school start later. Some teenagers might not go to school in the day; they wouldn’t be affected by the later school start.
D
Many of the car accidents involving teenage drivers in Granville occurred in the evening rather than in the morning.
We still know that after the Granville school’s start time was changed, the overall number of car accidents involving teenage drivers declined. Maybe some of the decrease relates to the evening; the rest could relate to the morning.
E
Car accidents involving teenage drivers rose in the region surrounding Granville during the time they declined in Granville.
This strengthens by eliminating the possibility that the decreased accidents in Granville were simply the result of a region-wide trend unconnected to the change in school start time.
Summary
Most of the new cars that Regis Motors sold last year were purchased by Blomenville residents. Still, most new cars purchased by Blomenville residents were not purchased from Regis Motors. However, Regis Motors sold more new cars last year than it did in any previous year.
Notable Valid Inferences
Last year Blomenville residents purchased a greater number of new cars than Regis Motors sold.
A
Regis Motors sold more new cars to residents of Blomenville last year than they had in any previous year.
Could be false. The stimulus tells us Regis sold more new cars last year than it did in any previous year, but we do not know that if these new cars were sold to Blomenville residents. It is possible that Regis sold more new cars to Blomenville residents in previous years.
B
The total number of new cars purchased by residents of Blomenville was greater last year than it was in any previous year.
Could be false. The stimulus does not give us any information about the number of cars Blomenville residents purchased in other years. It is possible that residents purchased more cars in previous years compared to last year.
C
A car retailer other than Regis Motors sold the most new cars to residents of Blomenville last year.
Could be false. We don’t know from the stimulus how many other car retailers other than Regis Motors sell to Blomenville residents. It is possible that Regis still sold most of the new cars to residents.
D
The number of new cars purchased last year by residents of Blomenville is greater than the number of new cars sold by Regis Motors.
Must be true. If most new cars that residents purchased were not from Regis Motors, and most new cars sold by Regis were purchased by residents, then it must be true that the total number of new cars purchased by residents is greater than the total number of cars sold by Regis.
E
Regis Motors’ share of the new car market in Blomenville last year increased over its share the year before.
Could be false. The stimulus does not give us any information about Regis Motor’s market share to make this claim. We cannot assume that just because Regis sold more new cars that their market share increased.