Summary
Every sale item purchased can be returned for store credit, but not returned for a refund. Every home appliance and every piece of gardening equipment is on sale. Some construction tools are on sale.
Notable Valid Inferences
Every home appliance can be returned for store credit
No home appliance can be returned for a refund
Every piece of gardening equipment can be returned for store credit
No piece of gardening equipment can be returned for a refund
Some construction tools can be returned for store credit
Some construction tools cannot be returned for a refund
No home appliance can be returned for a refund
Every piece of gardening equipment can be returned for store credit
No piece of gardening equipment can be returned for a refund
Some construction tools can be returned for store credit
Some construction tools cannot be returned for a refund
A
Any item that is not a home appliance or a piece of gardening equipment is returnable for a refund.
Could be false. This answer is a mistaken negation. The correct contrapositive would state that any item returnable for a refund is not a home appliance or a piece of gardening equipment.
B
Any item that is not on sale cannot be returned for store credit.
Could be false. The stimulus is limited to sale items. Items that are not on sale are outside of the scope of our conditions. It could be that some items that are not on sale cannot be returned for store credit.
C
Some construction tools are not returnable for store credit.
Could be false. We know from our conditions that some construction tools can be returned for store credit, but this does not imply that there are some tools that cannot be returned for store credit. The quantifier “some” has the possibility of meaning “all.”
D
No piece of gardening equipment is returnable for a refund.
Must be true. As shown below, we can chain our conditional claims and see that any piece of gardening equipment cannot be returned for a refund. 
E
None of the things that are returnable for a refund are construction tools.
Could be false. We know from our conditions that some construction tools are not returnable for a refund, but this does not imply that nothing returnable for a refund is a construction tool. We cannot take the contrapositive of a “some” statement.
Summary
The conclusion is that if broad mastery isn’t achieved, it must be that the students aren’t taught with appropriate methods. As support, the author gives a conditional premise: appropriate methods, combined with significant effort, lead to broad mastery. (Contrapositive: if broad mastery isn’t achieved, there either weren’t appropriate methods or there wasn’t significant effort.)
Missing Connection
The premise says that a lack of broad mastery means one of two things: a lack of appropriate methods or a lack of significant effort. But the conclusion is that broad mastery means one thing only: a lack of appropriate methods.
The conclusion would follow if we assumed that when there’s a lack of significant effort, there must also be a lack of appropriate methods. In that case, no matter what, a lack of broad mastery always means a lack of appropriate methods.
The conclusion would follow if we assumed that when there’s a lack of significant effort, there must also be a lack of appropriate methods. In that case, no matter what, a lack of broad mastery always means a lack of appropriate methods.
A
As long as secondary school students are taught with methods appropriate to their learning styles, they will devote significant effort to their studies.
Contrapositive: if students don’t devote significant effort, it must be that they’re not taught with appropriate methods. This means that no matter what, a lack of broad mastery means that student’s aren’t being taught with appropriate methods.
B
Even if secondary school students are taught with methods appropriate to their learning styles, they will not achieve broad mastery of the curriculum if they do not devote significant effort to their studies.
This says a lack of significant effort is sufficient for a lack of broad mastery. But this doesn’t change the argument’s core problem: a lack of broad mastery can mean either a lack of appropriate methods or a lack of significant effort. We’re still no closer to the conclusion.
C
Secondary school students do not achieve broad mastery of the curriculum if they are not taught with methods appropriate to their learning styles.
This says a lack of appropriate methods is sufficient for a lack of broad mastery. But this doesn’t change the argument’s core problem: a lack of broad mastery can mean either a lack of appropriate methods or a lack of significant effort. We’re still no closer to the conclusion.
D
Teaching secondary school students with methods appropriate to their learning styles does not always result in broad mastery of the curriculum by those students.
This breaks the argument. If appropriate methods aren’t sufficient for broad mastery, then the author can’t possibly conclude that a lack of broad mastery always implies a lack of appropriate methods.
E
Secondary school students who devote significant effort to their studies do not always achieve broad mastery of the curriculum.
So significant effort isn’t sufficient on its own for broad mastery. This doesn’t affect the argument, which says significant effort is sufficient if combined with appropriate methods. It’s still possible a lack of broad mastery sometimes implies a lack of significant effort.
Summarize Argument
The author’s main conclusion is that increasing urbanization might reduce the total amount of pollution in the nation. This is because people in more urban areas tend to rely more on mass transit and live in more energy-efficient houses than people in more rural areas. The same number of people in an urban area will produce less pollution than the same number of people in a rural area.
Identify Argument Part
The referenced text is the conclusion of the argument.
A
It is used to support the conclusion that people should live in large cities.
The referenced text is not a conclusion. Also, the author never suggests people should live in large cities.
B
It is a statement offered to call into question the claim that large cities are generally more polluted than the countryside.
The author concedes that large cities are generally more polluted than the countryside. This is not called into question by the author.
C
It is a statement serving merely to introduce the topic to be addressed in the argument and plays no logical role.
The referenced text is the conclusion.
D
It is a premise offered in support of the conclusion that large cities are generally more polluted than the countryside.
The referenced text is the conclusion. The claim that large cities are more polluted than the countryside is a concession.
E
It is a claim that the rest of the argument is designed to establish.
This accurately describes the role of the referenced text. It’s a conclusion supported by the claim that a given number of people will produce less pollution if concentrated in a large city than if dispersed among many small towns.
A science class stored one selection of various fruits at 30 degrees Celsius, a similar selection in similar conditions at 20 degrees, and another similar selection in similar conditions at 10 degrees. Because the fruits stored at 20 degrees stayed fresh longer than those stored at 30 degrees, and those stored at 10 degrees stayed fresh longest, the class concluded that the cooler the temperature at which these varieties of fruits are stored, the longer they will stay fresh.
Summarize Argument
The class concludes that the colder the storage conditions for these fruits, the longer they will stay fresh. They support this with an experiment in which similar fruits were stored at 30, 20, and 10 degrees in similar conditions. The fruits at 20 degrees lasted longer than those at 30 degrees, and the ones at 10 degrees stayed fresh the longest.
Identify and Describe Flaw
The class’s reasoning is flawed because they draw a broad conclusion based on a small range of temperatures (10-30 degrees). They assume that colder storage always keeps the fruits fresh for longer, ignoring the possibility that there could be temperatures that are too cold. In other words, just because the fruits lasted longer at 10 degrees than at 30 doesn’t mean they’ll last longer at 0 degrees.
A
generalized too readily from the fruits it tested to fruits it did not test
This is the cookie-cutter flaw of hasty generalization. The class doesn't make a generalization about fruits that they did not test. Instead, they draw a conclusion about “these varieties of fruits,” meaning the fruits that they did test.
B
ignored the effects of other factors such as humidity and sunlight on the rate of spoilage
The class doesn’t mention other factors, but it doesn’t need to because the experiment controlled for them. By keeping the other conditions similar for each selection of fruits, the class tested the effect of temperature.
C
too readily extrapolated from a narrow range of temperatures to the entire range of temperatures
The experiment showed that within the narrow range of 10-30 degrees, colder storage keeps the fruits fresh longer. They then apply this to all temperatures, assuming that colder storage always works, without considering that some temperatures might be too cold.
D
assumed without proof that its thermometer was reliable
The class never mentions a thermometer at all. Even if they did, we have no reason to believe that the thermometer might be unreliable. The flaw in the class’s argument has to do with how they apply their experiment’s findings, not with their thermometer.
E
neglected to offer any explanation for the results it discovered
The class concludes that colder storage helps the fruits last longer; they don't need to explain why. Even if they did explain why, this wouldn’t fix the fact that they apply their results too broadly.
Summarize Argument
The author concludes that a new technology that derives an oil from sewage sludge makes it possible that we can turn away from nuclear power and move towards environment-friendly energy. His support is that this sewage-sludge oil can be used to generate power
Notable Assumptions
The author assumes that the oil derived from sewage sludge, along with the myriad alternatives listed, would in fact be able to replace nuclear power. He also assumes that doing so would in fact result in less environmental damage than nuclear power does, which means he believes the process of extracting and storing oil from sewage sludge isn’t as environmentally taxing as nuclear power. Finally, the author assumes that relying on sewage sludge isn’t as much of a danger as nuclear power.
A
whether the current methods of disposing of sewage sludge by dumping do environmental damage
If the current method of disposing of sewage sludge is environmentally harmful, then a process relying on sewage sludge would be environmentally harmful. This would weaken the author’s argument that sewage-sludge oil will be environmentally beneficial versus nuclear power.
B
whether the processes that are used to turn sewage into clean water and sewage sludge have been improved in recent decades
Irrelevant. We don’t care if sewage sludge and water are being properly separated. We’re interested in whether an oil extracted from sewage sludge can in fact help replace nuclear power.
C
whether the cost of producing and using oil from sewage sludge would be economically sustainable
If producing and using an oil from sewage sludge isn’t economically sustainable, then that oil certainly won’t replace nuclear power. If it is economically sustainable, then the author’s argument in favor of that oil is strengthened.
D
whether the burning of oil from sewage sludge would, in contrast to nuclear power production, produce gases that would have a harmful warming effect on climate worldwide
If burning that oil did produce harmful gases—an effect that nuclear power production doesn’t have—then the author’s claim that the sewage-sludge oil offers an environmentally-friendly alternative to nuclear power is seriously undermined.
E
whether waste products that would be produced in deriving oil from sewage sludge and burning it would be as dangerous as those produced by the mining and use of nuclear fuel
If such products were produced, then sewage-sludge oil would seem to have one of the same problems the author cites about nuclear power: danger to humans.