两道GWD数学题

xiaoqing508

在版里找了很久以前的讨论汇总贴，都没有找到。无奈只能在此求助NN再帮我分析一下这两道题目。谢谢~~

1、

	Favorable	Unfavorable	Not Sure
Candidate M	40	20	40
Candidate N	30	35	35

 

 

The table above shows the results of a survey of 100 voters each responded “favorable” or “unfavorable” or “not sure” when asked about their impressions of candidate M and of candidate N.  What was the number of voters who responded “favorable” for both candidates?

(1)   The number of voters who did not respond “favorable” for either candidate was 40.

(2)     The number of voters who responded “unfavorable” for both candidates was 10.

                  

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.

答案是A。

我选的是E，特别是看不太懂（1）的意思。

2、

Q10:

A certain quantity is measured on two different scales, the R-scale and the S-scale, that are related linearly.  Measurements on the R-scale of 6 and 24 correspond to measurements on the S-scale of 30 and 60, respectively.  What measurement on the R-scale corresponds to a measurement of 100 on the S-scale?

 

 

A.     20

B.     36

C.     48

D.     60

E.      84

答案C。不知道从何处下手。

Q10:

A certain quantity is measured on two different scales, the R-scale and the S-scale, that are related linearly.  Measurements on the R-scale of 6 and 24 correspond to measurements on the S-scale of 30 and 60, respectively.  What measurement on the R-scale corresponds to a measurement of 100 on the S-scale?

 

 

A.     20

B.     36

C.     48

D.     60

E.      84

答案C。不知道从何处下手。

[此贴子已经被作者于2009/7/24 17:55:16编辑过]

lamour8828

第二题就是列两个方程嘛，

6a+b=30

24a+b=60

a=5/3

b=20

则5/3x+20=100的话，x=48咯

lamour8828

第一题的话估计就是拿100-40=60了

把（1）取非就是say favorable to both咯

xiaolishally

up

INCHASEDREAM

这个解释貌似不对，因为表格里注明了，M/N的各自的favo。

绝对不是取非这么简单。

INCHASEDREAM

请NN继续解答。。。。

dabobowa1111

第一题的解答：

设p(a)为favorable M的人概率，p(b)为favorable N的人的概率，那么就是求P(ab)*100的数量

因为P(a+b)=p(a)+p(b)-p(ab)

条件一：did not respond “favorable” for either candidate （包括unfavorable 和unsure的）取反是respond '''favorable' for either candidate，也就是p（a+b）*N=60

那么可得：p（ab）=10

条件二：无法判断

xiaoqing508

xiaoqing508

谢谢各位~

INCHASEDREAM