天山4-24请问
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

如何求解?
Ans = A