lsat-5-2-12

caterpillar

12. Photovoltaic power plants produce electricity from sunlight. As a result of astonishing recent technological advances, the cost of producing electric power at photovoltaic power plants, allowing for both construction and operating costs, is one-tenth of what it was 20 years ago, whereas the corresponding cost for traditional plants, which burn fossil fuels, has increased. Thus, photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do traditional power plants.

The conclusion of the argument is properly drawn if which one of the following is assumed?

(A) The cost of producing electric power at traditional plants has increased over the past 20 years.

(B) Twenty years ago, traditional power plants were producing 10 times more electric power than were photovoltaic plants.

(C) None of the recent technological advances in producing electric power at photovoltaic plants can be applied to producing power at traditional plants.

(D) Twenty years ago, the cost of producing electric power at photovoltaic plants was less than 20 times the cost of producing power at traditional plants.

(E) The cost of producing electric power at photovoltaic plants is expected to decrease further, while the cost of producing power at traditional plants is not expected to decrease.
答案是D
我怎么觉得正确答案应该是less than 10 times 而不是20times?

番茄炒蛋

数学问题
应该是二十倍了
这样在成本减少了10倍之后才会仍然比烧媒发电的贵，性价比不高嘛
自己举个例子吧，数字很能说明问题

caterpillar

但是结论是：Thus, photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do traditional power plants.
也就是说，比烧煤发电便宜呀？

睡熊

caterpillar: you are right, this is a mistake in yellow book (or elast), it is 10 times, not 20 times, i happen to have access to the original lsat publication

joice

Thanks. 睡熊

caterpillar

真的吗？那太感谢你了，睡熊。只是不知道LSAT题里还有多少错误呢.sigh

睡熊

不客气，joice 和 caterpillar MM.

crusaders

支持 :]
up

番茄炒蛋

嗯，真是粗心了一把
光想着只要煤电的成本只要增加了在两倍以上就可以得出结论了，可是如果按照原题，如果煤电的成本增加了不到两倍，原文的结论可能就不对了。
elsat中有好些遗漏和错误，下次真要有人修订一下就好了