1.(Z1-13)In the United States, of the people who moved from one state to another when they retired, the percentage who retired to Florida has decreased by three percentage points over the past ten years. Since many local businesses in Florida cater to retirees, this decline is likely to have a noticeably negative economic effect on these businesses.
Which of the following, if true, most seriously weakens the argument?
A. Florida attracts more people who move from one state to another when they retire than does any other state.
B. The number of people who move out of Florida to accept employment in other states has increased over the past ten years.
C. There are far more local businesses in Florida that cater to tourists than there are local businesses that cater to retirees.
D. The total number of people who retired and moved to another state for their retirement has increased significantly over the past ten years.
E. The number of people who left Florida when they retired to live in another state was greater last year than it was ten years ago.
2.(Z3)Kate: The recent decline in numbers of the Tennessee warbler, a North American songbird that migrates each fall to coffee plantations in South America, is due to the elimination of the dense tree cover that formerly was a feature of most South American coffee plantations.
Scott: The population of the spruce budworm, the warbler’s favorite prey in North America, has been dropping. This is a more likely explanation of the warbler’s decline.
Which of the following, if true, most seriously calls Scott’s hypothesis into question?
A. The numbers of the Baltimore oriole, a songbird that dose not eat budworms but is as dependent on South American coffee plantations as is the Tennessee warbler, are declining.
B. The spruce-budworm population has dropped because of a disease that can infect budworms but not Tennessee warblers.
C. The drop in the population of the spruce budworm is expected to be only temporary.
D. Many Tennessee warbler have begun migrating in the fall to places other than traditional coffee plantations.
E. Although many North American songbirds have declined in numbers, no other species has experienced as great a decline as has the Tennessee warbler.
3.(Z4)Proposal: Carbon dioxide and methane in the atmosphere block the escape of heat into space. So emission of these “greenhouse” gases contributes to global warming. In order to reduce global warming, emission of greenhouse gases needs to be reduced. Therefore, the methane now emitted from open landfills should instead be burned to produce electricity.
Objection: The burning of methane generates carbon dioxide that is released into the atmosphere.
Which of the following, if true, most adequately counters the objection made to the proposal?
A. Every time a human being or other mammal exhales, there is some carbon dioxide released into the air.
B. The conversion of methane to electricity would occur at a considerable distance from the landfills.
C. The methane that is used to generate electricity would generally be used as a substitute for a fuel that does not produce any greenhouse gases when burned.
D. Methane in the atmosphere is more effective in blocking the escape of heat from the Earth than is carbon dioxide.
E. The amount of methane emitted from the landfills could be reduced if the materials whose decomposition produces methane were not discarded, but recycled.
4.(Z4)It is theoretically possible that bacteria developed on Mars early in its history and that some were carried to Earth by a meteorite. However, strains of bacteria from different planets would probably have substantial differences in protein structure that would persist over time, and no two bacterial strains on Earth are different enough to have arisen on different planets. So, even if bacteria did arrive on Earth from Mars, they must have died out.
The argument is most vulnerable to which of the following criticisms?
A. It fails to establish whether bacteria actually developed on Mars.
B. It fails to establish how likely it is that Martian bacteria were transported to Earth.
C. It fails to consider whether there were means other than meteorites by which Martian bacteria could have been carried to Earth.
D. It fails to consider whether all bacteria now on Earth could have arisen from transported Martian bacteria.
E. It fails to consider whether there could have been strains of bacteria that originated on Earth and later died out.
5.(Z5)Insect infestations in certain cotton-growing regions of the world have caused dramatic increase in the price of cotton on the world market. By contrast, the price of soybeans has long remained stable. Knowing that cotton plants mature quickly, many soybean growers in Ortovia plan to cease growing soybeans and being raising cotton instead, thereby taking advantage of the high price of cotton to increase their income significantly, at least over the next several years.
Which of the following, if true, most seriously weakens the plan’s chances for success?
A. The cost of raising soybeans has increased significantly over the past several year and is expected to continue to climb.
B. Tests of a newly developed, inexpensive pesticide have shown it to be both environmentally safe and effective against the insects that have infested cotton crops.
C. In the past several years, there has been no sharp increase in the demand for cotton and for goods made out of cotton.
D. Few consumers would be willing to pay significantly higher prices for cotton goods than they are now paying.
E. The species of insect that has infested cotton plants has never been known to attack soybean plants.
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