[求助]GWD-7-9

remona9t

Q9:

Yesterday Diana spent a total of 240 minutes attending a training class, responding to E-mails, and talking on the phone.  If she did no two of these three activities at the same time, how much time did she spend talking on the phone?

(1)   Yesterday the amount of time that Diana spent attending the training class was 90 percent of the amount of time that she spent responding to E-mails.

(2)   Yesterday the amount of time that Diana spent attending the training class was 60 percent of the total amount of time that she spent responding to E-mails and talking on the phone.

                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

Answer: E

答案给的是C, 都快疯了，请大家帮我看看我的问题在那？

设the amount of time that Diana spent attending the training class is X; the amount of time that Diana responding to Emails is Y; the amount of time that Diana talking on the phone is Z;

则根据第一个条件：X=90%Y ; 根据第二个条件：X= 60%(Y+Z);

将第一个公式代入得：90%Y=60%(Y+Z) => 30%Y=60%Z => Y=2Z;

so: 三部分的时间分别为：X=90%Y; Y; 50%Y;  与所给的前提条件不符；所以选择答案E； 没想通为什么错了，请大家看看！

remona9t

顶一下

happyfish0517

1、2合起来...

设参加培训课的时间是x，根据条件1 可知，回复email的时间是10x/9

根据2可知，回复email的时间+打电话的时间总共是10x/6

so打电话的时间是10x/6-10x/9=5x/9

因为总时间是240分钟啊...即x+10x/6=8x/3=240,所以x=90分钟啦，所以打电话的时间是50分钟。

s 三部分的时间分别为：X=90%Y; Y; 50%Y;  与所给的前提条件不符；

我不大明白你这句话什么意思...与前提条件不符？

你忘了用那个总时间240分钟的条件了...

remona9t

If she did no two of these three activities at the same time,

没有看清楚no,哎，今天状态太差了！！！

谢谢楼上！

jingle0915

谢谢