概率问题,The following table summarizes the results of a poll taken of CEOs a border, economic, positive, following, face

jamsonsu

The following table summarizes the results of a poll taken of CEOs and analysts about the economic impact of a pending piece of legislation:

Group	Think the legislation will have a positive impact.	Think the legislation will have a negative impact.	Total
Others	40	30	70
Analysts	100	30	130
Total	140	60	200

What is the probability that a randomly selected individual from this group will be either an analyst or someone who thinks this legislation will have a positive impact on the economy?

A. 0.35.

B. 0.58.

C. 0.64.

None of the above

[此贴子已经被venson于2005-11-26 22:49:31编辑过]

m010915

统计还没有开始看呢。不过我觉得是“NONE OFTHE ABOVE” ，错了，别打噢。

m010915

我的算法； (40/200)*(70/200)+(100/200)*(130/200) = 0.395 大家切磋一下。本人离开学校有一段时间了。

whitetea

LZ有无正确答案啊？

ardenzhao

正确答案是什么啊？

stagqub

以下是引用m010915在2005-7-11 14:41:00的发言：

我的算法； (40/200)*(70/200)+(100/200)*(130/200) = 0.395   大家切磋一下。本人离开学校有一段时间了。

stagqub

just try

P(A or B) = P(A)+P(B)-P(A and B)=0.85

so m010915's answer seems to be incorrect.

I prefer the last answer "none of the above".

[此贴子已经被作者于2006-7-4 2:36:55编辑过]

yjy961

以下是引用stagqub在2006-7-4 2:35:00的发言：

just try

P(A or B) = P(A)+P(B)-P(A and B)=0.85

so m010915's answer seems to be incorrect.

I prefer the last answer "none of the above".

cuiww2008

版主，咱们论坛有没有开设CFA的QQ群呢？

谢谢

[em01]

lanlan2006

answer A

P(analysts)=130/200=13/20

P(Positive impact)=140/200=14/20

P(analyst and Positive impact)=100/200=10/20

P (Answer) = 13/20+14/20-12/20=7/20=0.35