Critical Reasoning

A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals that are toxic to most other plants. Agronomists studying the growth of this herb have discovered that it produces large amounts of histidine, an amino acid that, in test-tube solutions, renders these metals chemically inert. Hence, the herb's high histidine production must be the key feature that allows it to grow in metal-rich soils. B Whether others of the closely related group of plants also produce histidine in large quantities C Whether the herb's high level of histidine production is associated with an unusually low level of production of some other amino acid D Whether growing the herb in soil with high concentrations of the metals will, over time, reduce their concentrations in the soil E Whether the concentration of histidine in the growing herb declines as the plant approaches maturity

Economist: Tropicorp, which constantly seeks profitable investment opportunities, has been buying and clearing sections of tropical forest for cattle ranching, although pastures newly created there become useless for grazing after just a few years. The company has not gone into rubber tapping, even though greater profits can be made from rubber tapping, which leaves the forest intact. Thus, some environmentalists argue that Tropicorp's actions do not serve even its own economic interest. However, the initial investment required for a successful rubber-tapping operation is larger than that needed for a cattle ranch; there is a shortage of workers employable in rubber-tapping operations; and taxes are higher on profits from rubber tapping than on profits from cattle ranching. Consequently, the environmentalists' conclusion is probably wrong. In the economist's argument, the two boldface portions play which of the following roles?

Many agriculturally intensive areas of the world are beginning to encounter water scarcity problems. As a result, many farmers in these areas are likely to reduce their output as the water supply they need in order to maintain production shrinks. However, one group of farmers in such a region plans to increase their production by implementing techniques for water conservation. Which of the following, it true, would most strongly support the prediction that the group's plan will succeed?

Shipping Clerk: The five specially ordered shipments sent out last week were sent out on Thursday. Last week, all of the shipments that were sent out on Friday consisted entirely of building supplies, and the shipping department then closed for the weekend. Four shipments were sent to Truax Construction last week, only three of which consisted of building supplies. If the shipping clerk�s statements are true, which of the following must also be true?

Previously, Autoco designed all of its cars itself and then contracted with specialized parts suppliers to build parts according to its specifications. Now it plans to include its suppliers in designing the parts they are to build. Since many parts suppliers have more designers with specialized experience than Autoco has, Autoco expects this shift to reduce the overall time and cost of the design of its next new car. Which of the following, if true, most strongly supports Autoco�s expectation?

The average hourly wage of television assemblers in Vernland has long been significantly lower than that in neighboring Borodia. Since Borodia dropped all tariffs on Vernlandian televisions three years ago, the number of televisions sold annually in Borodia has not changed. However, recent statistics show a drop in the number of television assemblers in Borodia. Therefore, updated trade statistics will probably indicate that the number of televisions Borodia imports annually from Vernland has increased. Which of the following is an assumption on which the argument depends?

In Kravonia, the average salary for jobs requiring a college degree has always been higher than the average salary for jobs that do not require a degree. Current enrollments in Kravonia's colleges indicate that over the next four years the percentage of the Kravonian workforce with college degrees will increase dramatically. Therefore, the average salary for all workers in Kravonia is likely to increase over the next four years. Which of the following is an assumption on which the argument depends?

In an experiment, each volunteer was allowed to choose between an easy task and a hard task and was told that another volunteer would do the other task. Each volunteer could also choose to have a computer assign the two tasks randomly. Most volunteers chose the easy task for themselves and under questioning later said they had acted fairly. But when the scenario was described to another group of volunteers, almost all said choosing the easy task would be unfair. This shows that most people apply weaker moral standards to themselves than to others. Which of the following is an assumption required by this argument?

Advertisement: Our competitors' computer salespeople are paid according to the value of the products they sell, so they have a financial incentive to convince you to buy the most expensive units�whether you need them or not. But here at Comput-o-Mart, our salespeople are paid a salary that is not dependent on the value of their sales, so they won't try to tell you what to buy. That means when you buy a computer at Comput-o-Mart, you can be sure you're not paying for computing capabilities you don't need. Which of the following would, if true, most weaken the advertisement's reasoning?

Exporters in Country X are facing lower revenues due to a shortage of the large metal shipping containers in which they send their goods by sea to other countries. Fewer containers arrive in Country X due to reductions in imports. This has meant lost orders, costly delays, and a scramble for alternatives, such as air freight, all of which are costlier. Moreover, the revenues of exporters in Country X will probably continue to decline in the near future. This is because other countries are likely to find it increasingly unprofitable to export their goods to Country X, and because __________. Which of the following would most logically complete the passage?

Last year a global disturbance of weather patterns disrupted harvests in many of the world's important agricultural areas. Worldwide production of soybeans, an important source of protein for people and livestock alike, was not adversely affected, however. Indeed, last year's soybean crop was actually slightly larger than average. Nevertheless, the weather phenomenon is probably responsible for a recent increase in the world price of soybeans. Which of the following, if true, provides the strongest justification for the attribution of the increase in soybean prices to the weather phenomenon?

Consultant: Ace Repairs ends up having to redo a significant number of the complex repair jobs it undertakes, but when those repairs are redone, they are invariably done right. Since we have established that there is no systematic difference between the mechanics who are assigned to do the initial repairs and those who are assigned to redo unsatisfactory jobs, we must reject the hypothesis that mistakes made in the initial repairs are due to the mechanics' lack of competence. Rather, it is likely that complex repairs require a level of focused attention that the company's mechanics apply consistently only to repair jobs that have not been done right on the first try. In the consultant's reasoning, the two portions in boldface play which of the following roles?

Astronomer: Most stars are born in groups of thousands, each star in a group forming from the same parent cloud of gas. Each cloud has a unique, homogeneous chemical composition. Therefore, whenever two stars have the same chemical composition as each other, they must have originated from the same cloud of gas. Which of the following, if true, would most strengthen the astronomer�s argument?

Archaeologists use technology to analyze ancient sites. It is likely that this technology will advance considerably in the near future, allowing archaeologists to gather more information than is currently possible. If they study certain sites now, they risk contaminating or compromising them for future studies. Therefore, in order to maximize the potential for gathering knowledge in the long run, a team of archaeologists plans to delay the examination of a newly excavated site. Which of the following would be most useful to investigate for the purpose of evaluating the plan�s prospects for achieving its goal?

Plant scientists have used genetic engineering on seeds to produce crop plants that are highly resistant to insect damage. Unfortunately, the seeds themselves are quite expensive, and the plants require more fertilizer and water to grow well than normal ones. Accordingly, for most farmers the savings on pesticides would not compensate for the higher seed costs and the cost of additional fertilizer. However, since consumer demand for grains, fruits, and vegetables grown without the use of pesticides continues to rise, the use of genetically engineered seeds of this kind is likely to become widespread. In the argument given, the two portions in boldface play which of the following roles?

Farmer: Several people in the past few years have claimed to have seen a mountain lion in the suburban outskirts�the latest just last month�and, while mountain lions were thought to have been driven from this entire region about twenty years ago, there is no reason for the people who reported seeing a mountain lion to have deliberately concocted a false report. Therefore, local wildlife managers should begin to urgently address the mountain lion's presence. Which of the following would, if true, most seriously weaken the farmer's argument?

Advertisement: When your car�s engine is running at its normal operating temperature, any major brand of motor oil will protect it about as well as Tuff does. When the engine is cold, it is a different story: Tuff motor oil flows better at lower temperatures than its major competitors do. So, if you want your car�s engine to have maximum protection, you should use Tuff. Which of the following, if true, most strengthens the argument in the advertisement?

Regulations will not allow a pesticide that is toxic to humans to be used inside houses unless the pesticide will dissipate completely from the air within eight hours after its application. One test that pesticide manufacturers standardly use to determine how quickly anti-termite pesticides dissipate involves spraying the pesticides on the walls of room-sized plywood boxes and then timing its dissipation. Which of the following would it be most useful to know in order to evaluate whether a dissipation time of just under eight hours on the manufacturers� test indicates that an antitermite pesticide that is toxic to humans obeys regulations for use in houses?

Gortland has long been narrowly self-sufficient in both grain and meat. However, as per capita income in Gortland has risen toward the world average, per capita consumption of meat has also risen toward the world average, and it takes several pounds of grain to produce one pound of meat. Therefore, since per capita income continues to rise, whereas domestic grain production will not increase, Gortland will soon have to import either grain or meat or both. Which of the following is an assumption on which the argument depends?

Codex Berinensis, a Florentine copy of an ancient Roman medical treatise , is undated but contains clues to when it was produced. Its first 80 pages are by a single copyist, but the remaining 20 pages are by three different copyists, which indicates some significant disruption. Since a letter in handwriting identified as that of the fourth copyist mentions a plague that killed many people in Florence in 1148, Codex Berinensis was probably produced in that year. Which of the following, if true, most strongly supports the hypothesis that Codex Berinensis was produced in 1148?