2013年GMAT逻辑推理模拟训练（24）

　　25 Minutes 16 Questions

　　1. A report on acid rain concluded, “Most forests in Canada are not being damaged by acid rain.” Critics of the report insist the conclusion be changed to, “Most forests in Canada do not show visible symptoms of damage by acid rain, such as abnormal loss of leaves, slower rates of growth, or higher mortality.”

　　Which of the following, if true, provides the best logical justification for the critics’ insistence that the report’s conclusion be changed?

　　(A) Some forests in Canada are being damaged by acid rain.

　　(B) Acid rain could be causing damage for which symptoms have not yet become visible.

　　(C) The report does not compare acid rain damage to Canadian forests with acid rain damage to forests in other countries.

　　(D) All forests in Canada have received acid rain during the past fifteen years.(B)

　　(E) The severity of damage by acid rain differs from forest to forest.

　　2. In the past most airline companies minimized aircraft weight to minimize fuel costs. The safest airline seats were heavy, and airlines equipped their planes with few of these seats. This year the seat that has sold best to airlines has been the safest one—a clear indication that airlines are assigning a higher priority to safe seating than to minimizing fuel costs.

　　Which of the following, if true, most seriously weakens the argument above?

　　(A) Last year’s best-selling airline seat was not the safest airline seat on the market.

　　(B) No airline company has announced that it would be making safe seating a higher priority this year.

　　(C) The price of fuel was higher this year than it had been in most of the years when the safest airline seats sold poorly.

　　(D) Because of increases in the cost of materials, all airline seats were more expensive to manufacture this year than in any previous year.(E)

　　(E) Because of technological innovations, the safest airline seat on the market this year weighed less than most other airline seats on the market.

　　3. A computer equipped with signature-recognition software, which restricts access to a computer to those people whose signatures are on file, identifies a person’s signature by analyzing not only the form of the signature but also such characteristics as pen pressure and signing speed. Even the most adept forgers cannot duplicate all of the characteristics the program analyzes.

　　Which of the following can be logically concluded from the passage above?

　　(A) The time it takes to record and analyze a signature makes the software impractical for everyday use.

　　(B) Computers equipped with the software will soon be installed in most banks.

　　(C) Nobody can gain access to a computer equipped with the software solely by virtue of skill at forging signatures.

　　(D) Signature-recognition software has taken many years to develop and perfect.(C)

　　(E) In many cases even authorized users are denied legitimate access to computers equipped with the software.

　　4. Division manager: I want to replace the Microton computers in my division with Vitech computers.

　　General manager: Why?

　　Division manager: It costs 28 percent less to train new staff on the Vitech.

　　General manager: But that is not a good enough reason. We can simply hire only people who already know how to use the Microton computer.

　　Which of the following, if true, most seriously undermines the general manager’s objection to the replacement of Microton computers with Vitechs?

　　(A) Currently all employees in the company are required to attend workshops on how to use Microton computers in new applications.

　　(B) Once employees learn how to use a computer, they tend to change employers more readily than before.

　　(C) Experienced users of Microton computers command much higher salaries than do prospective employees who have no experience in the use of computers.

　　(D) The average productivity of employees in the general manager’s company is below the average productivity of the employees of its competitors.(C)

　　(E) The high costs of replacement parts make Vitech computers more expensive to maintain than Microton computers.

　　5. An airplane engine manufacturer developed a new engine model with safety features lacking in the earlier model, which was still being manufactured. During the first year that both were sold, the earlier model far outsold the new model; the manufacturer thus concluded that safety was not the customers’ primary consideration.

　　Which of the following, if true, would most seriously weaken the manufacturer’s conclusion?

　　(A) Both private plane owners and commercial airlines buy engines from this airplane engine manufacturer.

　　(B) Many customers consider earlier engine models better safety risks than new engine models, since more is usually known about the safety of the earlier models.

　　(C) Many customers of this airplane engine manufacturer also bought airplane engines from manufacturers who did not provide additional safety features in their newer models.

　　(D) The newer engine model can be used in all planes in which the earlier engine model can be used.(B)

　　(E) There was no significant difference in price between the newer engine model and the earlier engine model.

　　6. Between 1975 and 1985, nursing-home occupancy rates averaged 87 percent of capacity, while admission rates remained constant, at an average of 95 admissions per 1,000 beds per year. Between 1985 and 1988, however, occupancy rates rose to an average of 92 percent of capacity, while admission rates declined to 81 per 1,000 beds per year.

　　If the statements above are true, which of the following conclusions can be most properly drawn?

　　(A) The average length of time nursing-home residents stayed in nursing homes increased between 1985 and 1988.

　　(B) The proportion of older people living in nursing homes was greater in 1988 than in 1975.

　　(C) Nursing home admission rates tend to decline whenever occupancy rates rise.

　　(D) Nursing homes built prior to 1985 generally had fewer beds than did nursing homes built between 1985 and 1988.(A)

　　(E) The more beds a nursing home has, the higher its occupancy rate is likely to be.

　　7. Firms adopting “profit-related-pay” (PRP) contracts pay wages at levels that vary with the firm’s profits. In the metalworking industry last year, firms with PRP contracts in place showed productivity per worker on average 13 percent higher than that of their competitors who used more traditional contracts.

　　If, on the basis of the evidence above, it is argued that PRP contracts increase worker productivity, which of the following, if true, would most seriously weaken that argument?

　　(A) Results similar to those cited for the metalworking industry have been found in other industries where PRP contracts are used.

　　(B) Under PRP contracts costs other than labor costs, such as plant, machinery, and energy, make up an increased proportion of the total cost of each unit of output.

　　(C) Because introducing PRP contracts greatly changes individual workers’ relationships to the firm, negotiating the introduction of PRP contracts is complex and time consuming.

　　(D) Many firms in the metalworking industry have modernized production equipment in the last five years, and most of these introduced PRP contracts at the same time.(D)

　　(E) In firms in the metalworking industry where PRP contracts are in place, the average take-home pay is 15 percent higher than it is in those firms where workers have more traditional contracts.

　　8. Crops can be traded on the futures market before they are harvested. If a poor corn harvest is predicted, prices of corn futures rise; if a bountiful corn harvest is predicted, prices of corn futures fall. This morning meteorologists are predicting much-needed rain for the corn-growing region starting tomorrow. Therefore, since adequate moisture is essential for the current crop’s survival, prices of corn futures will fall sharply today.

　　Which of the following, if true, most weakens the argument above?

　　(A) Corn that does not receive adequate moisture during its critical pollination stage will not produce a bountiful harvest.

　　(B) Futures prices for corn have been fluctuating more dramatically this season than last season.

　　(C) The rain that meteorologists predicted for tomorrow is expected to extend well beyond the corn-growing region.

　　(D) Agriculture experts announced today that a disease that has devastated some of the corn crop will spread widely before the end of the growing season.(D)

　　(E) Most people who trade in corn futures rarely take physical possession of the corn they trade.