大全-5-19

financelover

Section5
19. Recent estimates predict that between 1982 and 1995 the greatest increase in the number of people employed will be in the category of low-paying service occupations. This category, however, will not increase its share of total employment, whereas the category of high-paying service occupations will increase its share.
If the estimates above are accurate, which of the following conclusions can be drawn?
(A) In 1982 more people were working in low-paying service occupations than were working in high-paying service occupations.
(B) In 1995 more people will be working in high-paying service occupations than will be working in low-paying service occupations.
(C) Nonservice occupations will account for the same share of total employment in 1995 as in 1982.
(D) Many of the people who were working in low-paying service occupations in 1982 will be working in high-paying service occupations by 1995.
(E) The rate of growth for low-paying service occupations will be greater than the overall rate of employment growth between 1982 and 1995.

不解请指教

albertjerrys

我来证明一下.
用l表示low-paying service,用h表示high-paying service,用t表示总人数.
于是从1982~1995数据的变化为:
l→l+δl,h→h+δh,t→t+δt,其中δt>δl>δh.
相应的low-paying和high-paying两伙人的占比变化就为:
l/t→(l+δl)/(t+δt), h/t→(h+δh)/(t+δt)

按照已知条件,l/t>(l+δl)/(t+δt) => (tδl-lδt)/[t(t+δt)]<0 => tδl-lδt<0 => δl/l<δt/t
             h/t>(h+δh)/(t+δt) => (tδh-hδt)/[t(t+δt)]>0 => tδh-hδt>0 => δh/h>δt/t
所以δh/h>δl/l,
考虑到δl>δh,
故有h<l,也就是说1982年的high-paying service的人数小于low-paying service的人数.

financelover

哎呀，我怎么搞的 原来我一直把“the greatest increase in the number of people employed ”理解成增加的速度了 难怪找不到答案  谢谢

veroniquelins

答案选a吧
这里出得问题就是百分比和实际数字得区别
如果工人增加10万人，可能百分比也增加不了多少，而ceo增加了1000，可能增幅就有100percent了
由增幅再反过来去推增量

ps，这个好像就是自由说到得逻辑数字题吧，但看清楚了就不会很麻烦了