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题库 / Prep2007E1-CR-58
Roland: The alarming fact is that 90 percent of the people in this country now report that they know someone who is unemployed.
Sharon: But a normal, moderate level of unemployment is 5 percent, with 1 out of 20 workers unemployed. So at any given time if a person knows approximately 50 workers, one or more will very likely be unemployed.
Sharon's argument relies on the assumption that
normal levels of unemployment are rarely exceeded
unemployment is not normally concentrated in geographically isolated segments of the population
the number of people who each know someone who is unemployed is always higher than 90 percent of the population
Roland is not consciously distorting the statistics he presents
knowledge that a personal acquaintance is unemployed generates more fear of losing one's job than does knowledge of unemployment statistics
sharon的argument可以看成
前提：正常的失业率5%，每20人有一个人失业
结论：一个人认识50个workers应该2.5人失业
推理方式：统计枚举推理
CQ1.样本的代表性，是不是正常的失业率也适用于a person
是assumption题，取反后可以weaken结论
b选项 取反 失业会集中在地理上闭塞的人群。所以使得结论2.5个人失业不成立，可能多也可能少于2.5个人。
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