蓝皮265 zoo aquarium & aquarium?

charlottecheng · 发表于 2010-4-4 21:21:00

in the united states, vacationers account for more than half of all visitors to what are technically called "pure aquariums" but for fewer than one quarter of all visitors to zoos, which usually include a "zoo aquarium" of relatively modest scope.
which of the following, if true, most helps to account for the difference described above between visitors to zoos and visitors to pure aquariums?
(a) in cities that have both a zoo and a pure aquarium, local residents are twice as likely to visit the aquarium as they are to visit the zoo
(b) virtually all large metropolitan areas have zoos, whereas only a few large metropolitan areas have pure aquariums.
(c) over the last ten years, newly constructed pure aquariums have outnumbered newly established zoos by a factor of two to one.
(d) people who visit a zoo in a given year are two times more likely to visit a pure aquarium that year than are people who do not visit a zoo.
(e) the zoo aquariums of zoos that are in the same city as a pure aquarium tend to be smaller than the aquariums of zoos that have no pure aquarium nearby.

答案是B，为什么不是D？D说去了zoo的人们会更想去aquarium （zoo里的aquarium规模小，人们便想去看大一点的），且人数是2倍多，看上去没什么不对，从人数上和题干上也能对应。

coolhaoming · 发表于 2010-4-5 00:10:38

D在数量上有一个严重的flaw，如果一共有100人。40人去过动物园，60人没去过。
40人中想去水族馆的可能性是60人中的2倍。
如果40人中去水族馆的可能性是10%，则60人中是20%。可以算出40人中有4人想去水族馆，60人中有12人想去。

这样人群中一共有16人想去，如果都去了，那么本年一共有16人去水族馆。可去动物园的却又40人。得出去动物园的人多。

关键是可能性问题，可能性是两个人群之间的比较，不能说明与基数之间的关系。

clumsy123 · 发表于 2011-4-21 14:05:50

能解释下为啥选B么？

蓝皮265 zoo aquarium & aquarium?

所属分类: GMAT考试

正在浏览此版块的会员 ()