标题: 求教GWD 1-14 [打印本页] 作者: 小小照妖镜 时间: 2011-7-12 16:24 标题: 求教GWD 1-14 That the application of new technology can increase the productivity of existing coal mines is demonstrated by the case of Tribnia’s coalindustry. Coaloutputperminerin Tribnia is double what it was five years ago, even though no new mines have opened.
Which of the following can be properly concluded from the statement about coaloutputperminerin the passage?
A. If the number of miners working in Tribnian coal mines has remained constant in the past five years, Tribnia’s total coal production has doubled in that period of time. B. Any individual Tribnian coal mine that achieved an increase in overall outputin the past five years has also experienced an increase inoutputperminer. C. If any new coal mines had opened in Tribnia in the past five years, then the increase inoutputperminer would have been even greater than it actually was. D. If any individual Tribnian coal mine has not increased its outputperminerin the past five years, then that mine’s overall output has declined or remained constant. E. In Tribnia the cost of producing a given quantity of coal has declined over the past five years.
see above -- it's possible that the mines added workers.
if a mine added workers, then its TOTAL OUTPUT could increase despite a decrease in the per-worker output. (i.e., think about 100 workers producing 3 units each, vs. 200 workers producing 2 units each.)
For C, because the number of miners working in Tribnian coal mines is indefinite, output per miner=total output/total miners, even the number of mines increased may lead to the increase of the total output, but the total miners might also get an increase, therefore, we cannot get a conclusion on the output per miner, just because there are two variables in the foresaid formula.作者: franciscomatt 时间: 2011-7-18 06:37
我觉得是A啊。。作者: sanlingjie 时间: 2011-7-18 10:41