16. A recent report determined that although only three percent of drivers on Maryland highways equipped their vehicles with radar detectors, thirty-three percent of all vehicles ticketed for exceeding the speed limit were equipped with them. Clearly, drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly than are drivers who do not.The conclusion drawn above depends on which of the following assumptions?
(A) Drivers who equip their vehicles with radar detectors are less likely to be ticketed for exceeding the speed limit than are drivers who do not.
(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly than are drivers who are not ticketed.
(C) The number of vehicles that were ticketed for exceeding the speed limit was greater than the number of vehicles that were equipped with radar detectors.
(D) Many of the vehicles that were ticketed for exceeding the speed limit were ticketed more than once in the time period covered by the report.（B）
(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.
17. There is a great deal of geographical variation in the frequency of many surgical procedures—up to tenfold variation per hundred thousand between different areas in the numbers of hysterectomies, prostatectomies, and tonsillectomies.To support a conclusion that much of the variation is due to unnecessary surgical procedures, it would be most important to establish which of the following?
(A) A local board of review at each hospital examines the records of every operation to determine whether the surgical procedure was necessary.
(B) The variation is unrelated to factors (other than the surgical procedures themselves) that influence the incidence of diseases for which surgery might be considered.
(C) There are several categories of surgical procedure (other than hysterectomies, prostatectomies, and tonsillectomies) that are often performed unnecessarily.
(D) For certain surgical procedures, it is difficult to determine after the operation whether the procedures were necessary or whether alternative treatment would have succeeded.（B）
(E) With respect to how often they are performed unnecessarily, hysterectomies, prostatectomies, and tonsillectomies are representative of surgical procedures in general.
18. Researchers have found that when very overweight people, who tend to have relatively low metabolic rates, lose weight primarily through dieting, their metabolisms generally remain unchanged. They will thus burn significantly fewer calories at the new weight than do people whose weight is normally at that level. Such newly thin persons will, therefore, ultimately regain weight until their body size again matches their metabolic rate.The conclusion of the argument above depends on which of the following assumptions?
(A) Relatively few very overweight people who have dieted down to a new weight tend to continue to consume substantially fewer calories than do people whose normal weight is at that level.
(B) The metabolisms of people who are usually not overweight are much more able to vary than the metabolisms of people who have been very overweight.
(C) The amount of calories that a person usually burns in a day is determined more by the amount that is consumed that day than by the current weight of the individual.
(D) Researchers have not yet determined whether the metabolic rates of formerly very overweight individuals can be accelerated by means of chemical agents.（A）
(E) Because of the constancy of their metabolic rates, people who are at their usual weight normally have as much difficulty gaining weight as they do losing it.
19. In 1987 sinusitis was the most common chronic medical condition in the United States, followed by arthritis and high blood pressure, in that order.The incidence rates for both arthritis and high blood pressure increase with age, but the incidence rate for sinusitis is the same for people of all ages.The average age of the United States population will increase between 1987 and 2000.Which of the following conclusions can be most properly drawn about chronic medical conditions in the United States from the information given above?
(A) Sinusitis will be more common than either arthritis or high blood pressure in 2000.
(B) Arthritis will be the most common chronic medical condition in 2000.
(C) The average age of people suffering from sinusitis will increase between 1987 and 2000.
(D) Fewer people will suffer from sinusitis in 2000 than suffered from it in 1987.（C）
(E) A majority of the population will suffer from at least one of the medical conditions mentioned above by the year 2000.
20. Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg. If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space. If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae.Which of the following conclusions can properly be drawn from the information above?
(A) The size of the smallest host egg that a wasp could theoretically parasitize can be determined from the wasp’s egg-laying behavior.
(B) Host insects lack any effective defenses against the form of predation practiced by parasitic wasps.
(C) Parasitic wasps learn from experience how many eggs to lay into the eggs of different host species.
(D) Failure to lay enough eggs would lead to the death of the developing wasp larvae more quickly than would laying too many eggs.（A）
(E) Parasitic wasps use visual clues to calculate the size of a host egg.
答案： 1. A 2. B 3. D 4. D 5. B 6. E 7. C 8. D 9. A 10. E 11. B 12. D 13. A 14. C 15. E 16. B 17. B 18. A 19. C 20. A
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