[問題]LSAT test 11-7

[shopcat]

7. Which of the following best completes the passage below?
The unemployment rate in the United States fell from 7.5 percent in 1981 to 6.9 percent in 1986. It cannot, however, be properly concluded from these statistics that the number of unemployed in 1986 was lower than it had been in 1981 because______
(A) help-wanted advertisements increased between 1981 and 1986
(B) many of the high-paying industrial jobs available in 1981 were replaced by low-wage service jobs in 1986, resulting in displacements of hundreds of thousands of workers
(C) in some midwestern industrial states, the unemployment rate was much higher in 1986 than it had been in 1981
(D) the total available work force, including those with and without employment, increased between 1981 and 1986
(E) the average time that employees stay in any one job dropped during the period 1981 to 1986

請教前輩
這題的題目是說:失業率從1981的7.5%降到1986年的6.9%,但是這項統計是不能下結論失業率是降低的,因為__________
D的選項說勞動力在1981到1986年之間是增加,包含有工作的跟沒有工作的
那這樣不就支持證明這個統計是可以下結論的,因為勞動力增加,失業率下降
這樣很合理ㄚ.
為何選Dㄋ?[/quote]

[micht]

分母變大 比例下降

for example,
1981, 1000人失業 total 10,000人
1986, 1000人失業 total 50,000人

不代表 失業的人找到工作ㄌ 沒有improved

[shopcat]

謝謝!我了解了. rate跟number是兩回事