GWD15-Q24~求助NN~

evelyn205205

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

答案：A。这道题怎么入手呢？

期待NN了~

bmwwhz

[1-(56%+48%-30%)]*1200=312

bmwwhz

刚画了个图，很直观地解释，可是不会贴图。
56%+48%是所有U，U&B,U&F的人加上F，F&U,F&B的人的总和，减去30%就是减去重复的那部分U&F。用总数1减去那部分，就是纯B的比例，乘以总人数就是纯B的人数。

[1-(56%+48%-30%)]*1200=312

-- by 会员 bmwwhz (2011/7/27 15:01:31)

evelyn205205

刚画了个图，很直观地解释，可是不会贴图。
56%+48%是所有U，U&B,U&F的人加上F，F&U,F&B的人的总和，减去30%就是减去重复的那部分U&F。用总数1减去那部分，就是纯B的比例，乘以总人数就是纯B的人数。

[1-(56%+48%-30%)]*1200=312

-- by 会员 bmwwhz (2011/7/27 15:01:31)

-- by 会员 bmwwhz (2011/7/27 15:21:32)

谢谢！！！