[求助]一道逻辑题百思不得其解

amo

陈向东逻辑推理的那本书中的题
15 In 1985 a consumer agency concluded that Xylo brand bicycles are safer to ride than are Zenon brand bicycles. The agency based the conclusion on the ratio of the number of rider injuries to the number of riding hours for each brand of bicycle from 1981 through 1984. Yet for identically designed bicycles manufactured since1985,the number of rider injuries has been twice as great among rifers of Xylos as among riders of Zenons. Therefore, the agency's conclusion would have been different for the period since1985.
Which of the following is an assumption that, if true, supports the claim that agency's conclusion would have been different for the period since 1985?
(A) For the period since 1985, the number of riding hours for Zenons totaled at least half the number of riding hours for Xylos.
答案是A，请问问题中“supports the claim that agency's conclusion would have been different for the period since 1985”究竟该如何理解？要有different不就是和agency原来的结论（1985年提出的结论）不同吗，那为什么A就是答案呢？

jediming

1985的结论来自于1981-1984的数据。现在1985又有新的数据，结论自然会不同。
题目说的different就是说在1985的数据的基础上得出的新结论,不同于1985提出的结论

weiyu

1. First you must know the scale standard: number of injuries(用I表示)/ number of riding hours(用H表示); the less    the ratio is, the safer for the according brand.


1984 conclusion: X is safer than Z;


1985 we conclude Iz/Hz<Ix/Hx，已知 Ix=2Iz; 所以要得到Iz/Hz<Ix/Hx要求Hz>Hx/2