Summary
When soil is plowed in the spring, pigweed seeds are churned up and redeposited just under the surface. Brief exposure to sunlight stimulates receptors. When receptors are stimulated, germination is triggered. Prolonged darkness, followed by exposure to sunlight, is necessary for the seeds to germinate.
Strongly Supported Conclusions
Fewer pigweed seeds will germinate when a field is plowed at night versus a field that is plowed during the day.
A
Fewer pigweed plants will grow in the field if it is plowed only at night than if it is plowed during the day.
This answer is strongly supported. The last sentence tells us that exposure to sunlight is necessary for seeds to germinate. There is no sunlight at night, therefore the seeds are less likely to grow.
B
Fewer pigweed plants will grow in the field if it is not plowed at all than if it is plowed only at night.
This answer is unsupported. We don’t know from the stimulus what occurs whenever a field is not plowed at all.
C
Fewer pigweed plants will grow in the field if it is plowed just before sunrise than if it is plowed just after sunset.
This answer is unsupported. Before sunrise and after sunset both imply darkness. Exposure to sunlight is necessary for seeds to germinate.
D
The pigweed seeds that are churned up to the surface of the soil during the plowing will not germinate unless they are redeposited under the surface of the soil.
This answer is unsupported. We don’t know from the stimulus whether the seeds being redeposited is a necessary condition for germination.
E
All of the pigweed seeds that are already on the surface of the soil before the field is plowed will germinate.
This answer is unsupported. The last sentence tells us that prolonged darkness is necessary for seeds to germinate. If the seeds are already on the surface, then they were not exposed to prolonged darkness.
Summarize Argument
The author concludes companies should assign their best managers to development projects. Why? Because talented managers are typically assigned to established projects, causing new product lines—which require talent to market—to fail most of the time.
Notable Assumptions
The author assumes assigning talented managers to development projects would create a net benefit to companies. This means assuming talented managers would increase the chances new projects succeed, and that the consequent benefit would outweigh any harm caused by removing skilled managers from established project lines.
A
On average, new ventures under the direction of managers at executive level survive no longer than those managed by lower-ranking managers.
This weakens the argument. It suggests assigning talented managers to new products would not make those products more successful on average.
B
For most established companies, the development of new product lines is a relatively small part of the company’s total expenditure.
If anything, this weakens the argument. It suggests new product lines are a small part of a company’s overall plan, which means assigning talented managers to those projects carries a larger risk.
C
The more talented a manager is, the less likely he or she is to be interested in undertaking the development of a new product line.
If anything, this weakens the argument. It suggests assigning managers to new product lines will result in more of a company’s talented managers working on projects they’re disinterested in.
D
The current revenue and profitability of an established product line can be maintained even if the company’s best managers are assigned elsewhere.
This supports the author’s recommendation by ruling out a possible problem. It suggests removing talented managers from established product lines will not substantially harm those product lines.
E
Early short-term revenue prospects of a new product line are usually a good predictor of how successful a product line will ultimately be.
This is irrelevant. The author doesn’t suggest experienced managers be assigned at a particular point in a new product’s development, nor does he suggest early revenue prospects are determined by managerial performance.
Summarize Argument
The researchers implicitly conclude that drinking just two cups of coffee per day gives them less risk of heart disease than drinking five or more cups per day. Why? Because their research found that people who drink five or more cups daily have an elevated risk of heart disease.
Notable Assumptions
The researchers assume that people who drink two cups of coffee per day have less risk of heart disease than those who drink five or more per day. They also assume there’s no factor besides age and smoking habits that is associated with coffee intake and would explain the health effect.
A
The study found that for people who drank three or more cups of coffee daily, the additional risk of heart disease increased with each extra daily cup.
This is irrelevant because it does not apply to people drinking two or fewer cups per day. It’s possible that people who drink two cups daily have an even higher risk of heart disease than people who drink five cups.
B
Per capita coffee consumption has been declining over the past 20 years because of the increasing popularity of soft drinks and also because of health worries.
The proportion of people in the world drinking coffee is not relevant to the researchers’ decision. Lots of coffee can have negative health effects even if it’s less popular than it used to be.
C
The study did not collect information that would show whether variations in level of coffee consumption are directly related to variations in level of stress, a major causal factor in heart disease.
This introduces an alternative explanation for the study’s results that challenges the researchers’ conclusion. If people who are stressed tend to consume lots of coffee, then simply reducing coffee intake may not reduce the risk of heart disease.
D
Subsequent studies have consistently shown that heavy smokers consume coffee at about 3 times the rate of nonsmokers.
The study controlled for smoking, so a relationship between smoking habits and coffee consumption should not have influenced the results.
E
Subsequent studies have shown that heavy coffee consumption tends to cause an elevated blood-cholesterol level, an immediate indicator of increased risk of heart disease.
This explains why drinking more coffee increases the risk of heart disease, without challenging the researchers’ conclusion. It does not imply that variations in blood-cholesterol levels confounded the study’s results.