寂静第三就是GWD15-24

JUDYLI

    

昨天刚做过，看一眼就想起来了。

Q24:

    

 

    
        
                
                
            
            
                
                
            
            
                
                
            
            
                
                
            
        

Factor	Percent of   Respondents
User-friendly	56%
Fast   response time	48%
Bargain   prices	42%

    

 

    

 

    

The table gives three factors to be considered when choosing
an Internet service provider and the percent of the 1,200 respondents to a
survey who cited that factor as important. 
If 30 percent of the respondents cited both “user-friendly” and “fast
response time,” what is the maximum possible number of respondents who cited
“bargain prices,” but neither “user-friendly” nor “fast response time?”

    

 

    

A.   
312

    

B.    
336

    

C.    
360

    

D.   
384

    

E.    
420

denverxu

答案是A吗？

lianghao

唉这题我还真不太会，谁能给解答一下怎么做？

onlyalittle

试着回答一下，
画韦恩图，U+F+B-UF-UB-FB-2UFB=100% AND UF=30
所求=B-UB-FB=100%+UF-U-F-2UFB=100%+30%-56%-48%-2UFB=26%-2UFB
当UFB=0时，即三个元素无共同交集时最大（26%）。1，200*26%=312

JUDYLI

楼上是对的