[求助]GMATprep

zora_zhu

1.The residents of town x participated in a survey to determine the number of hours per week each resident spent watching television. The distribtuion of the results of the survey had a mean of 21 hours and a stardard deviation of 6 hours. The number of hours that Pat, a resident of town x, watched television last week was between 1 and 2 standard deviations below the mean. Which of the following could be the number of hours that Pat watched television last week?

a.30  b.20. c. 18. d.12. e. 6

Answer is d. I have no idea about it.

2.Each employee on a certain task force is either a manager or a dirctor. What percent of the employees on the task force are directors?

The aswer is C. My choice is E. Why?

Tks.

sunshinerab

1，建议划一个number line很清楚的，将 21放在正中间，因为标准差6小时，所以21的左边是21-6=15小时，21的右边是21+6=27小时。又因为题目告知P 是1-2个标准低于mean, 所以P如果1个标准低于mean，那么P=21-6=15小时， 如果P是2个标准差低于mean，P=21-6*2=9， 答案只有12是位于15-9之间，所以为正确答案。
2。我不明白是什么意思，因为没有任何数字和条件。

zora_zhu

Sorry about the No 2, I forgot to put the conditions.

2.Each employee on a certain task force is either a manager or a dirctor. What percent of the employees on the task force are directors?

1, The average salary of managers on the task force is 5,000 less than the average salary of employees on the task force.

2.The average salary of directors on the task force is 15,000 more than the average salary of all employees on the task force.

The aswer is C. My choice is E. Why?

Tks.

sunshinerab

第二题
条件一和二均不成立，一起成立！！
设M有X人，D有Y人
5000X=15000Y
X：Y=3：1
Y/（X+Y）=25%

hitlzc

有GMATPREP题请优先搜索讨论稿，谢谢配合！

http://forum.chasedream.com/dispbbs.asp?BoardID=22&ID=171137&replyID=&skin=1

http://forum.chasedream.com/dispbbs.asp?boardid=22&id=150752&star=1#150752

洛拉

以下是引用sunshinerab在2006-6-25 11:25:00的发言：
第二题
条件一和二均不成立，一起成立！！
设M有X人，D有Y人
5000X=15000Y
X：Y=3：1
Y/（X+Y）=25%

2.Each employee on a certain task force is either a manager or a dirctor. What percent of the employees on the task force are directors?

(1)  The average salary of managers on the task force is 5,000 less than the average salary of employees on the task force.

(2) The average salary of directors on the task force is 15,000 more than the average salary of all employees on the task force

没有看懂sunshinerabMM的式子是什么意思？有谁能帮忙解释一下？这道题怎么算出的C