求助~GWD24-12

jessiecg

12
During a 10-week summer vacation, was the average (arithmetic mean) number of books that Carolyn read per week greater than the average number of books that Jacob read per week?

(1)Twice the average number of books that Carolyn read per week was greater than 5 less than twice the average number of books that Jacob read per week.


(2)During the last 5 weeks of the vacation, Carolyn read a total of 3 books more than Jacob.


答案是A,我选的E.
(1)这句话是什么意思啊？
是说：C所读的书的两倍比J所读的书的两倍多5本？
请牛人指导

jessiecg

自己顶一下~
希望大牛们快点儿指点~

alfxu

1的意思是不是5<2C<2J呢？那样的话1也不对啊，c读的没j多。

maximeason

不管求出哪个 都是条件充分 楼上你要理解清楚ds题的变态

我认为答案是e
2c>2j-5 是求不出c与j的关系的如果是 +5 可以稳定的推出c一定大于j
比如c是6 j是7  12必然大于>9 但是6<7  c是6 j是5 也是成立的 所以a求不出来

jessiecg

恩，明白了，谢谢大家~

zafteria

(1)Twice the average number of books that Carolyn read per week was greater than 5 less than twice the average number of books that Jacob read per week.
应该理解为2c>2J-5,不能推出c j的大小
应该选E，不过看了下答案，是A。。。

jessiecg

估计答案有问题~

昵昵大人

看了下，这道题2007年就有人问了，现在也没个定论
主要是Twice the average number of books that Carolyn read per week was greater than 5 less than twice the average number of books that Jacob read per week这句话太有歧义了
意思1：Twice the average number of books that Carolyn read per week was （greater than 5）（less than twice） the average number of books that Jacob read per week  就是5<2c<2j
意思2：Twice the average number of books that Carolyn read per week was greater than （5 less than twice） the average number of books that Jacob read per week 就是2c>2j-5

GWD的答案是A，所以如果从答案反推，应该是按意思1理解，但是总觉得从SC的角度来看，好像少点什么。。。。