[求助]求助几道GWD数学，实在不明白……谢谢前辈们拉

GWD31-13math-Q4:

Of the total amount that Jill spent on a shopping trip, excluding taxes, she spent 50 percent on clothing, 20 percent on food, and 30 percent on other items.  If Jill paid a 4 percent tax on the clothing, no tax on the food, and an 8 percent tax on all other items, then the total tax that she paid was what percent of the total amount that she spent, excluding taxes?

A.     2.8%

B.     3.6%

C.     4.4%

D.     5.2%

E.      6.0%                                                                      怎么做？

GWD31-13math-Q7:

For a certain race, 3 teams were allowed to enter 3 members each.  A team earned 6 – n points whenever one of its members finished in nth place, where 1 ≤ n ≤ 5.  There were no ties, disqualifications, or
     withdrawals.  If no team earned more than 6 points, what is the least possible score a team could have earned?

A.     0

B.     1

C.     2

D.     3

E.      4

看都看不懂……

GWD31-15math-Q24: 

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

这类题请前辈们指导，我一碰到这就头疼

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

这类题请前辈们指导，我一碰到这就头疼

For a certain race, 3 teams were allowed to enter 3 members each.  A team earned 6 – n points whenever one of its members finished in nth place, where 1 ≤ n ≤ 5.  There were no ties, disqualifications, or
     withdrawals.  If no team earned more than 6 points, what is the least possible score a team could have earned?

A.     0

B.     1

C.     2

D.     3

E.      4

看都看不懂……

GWD31-15math-Q24: 

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

这类题请前辈们指导，我一碰到这就头疼

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

这类题请前辈们指导，我一碰到这就头疼

GWD31-15math-Q28:

A school administrator will assign each student in a group of n students to one of m classrooms.  If 3 < m < 13 < n, is it possible to assign each of the n students to one of the m classrooms so that each classroom has the same number of students assigned to it?

(1)   It is possible to assign each of 3n students to one of m classrooms so that each classroom has the same number of students assigned to it.

(2)   It is possible to assign each of 13n students to one of m classrooms so that each classroom has the same number of students assigned to it.

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.

不知道这类题的解题思路

请各位前辈给予指点，不胜感激……

怎么改也改不掉？我好笨……

1. Please use TT GWD-xx-yy format.  For example, your first question would be TT GWD-13-4.

2. Please search for existing discussions before you post your questions.

http://forum.chasedream.com/dispbbs.asp?boardID=22&ID=184062&page=1

3. Please post your questions separately.  If the existing discussions are still confusing to you, please follow the thread and add your questions there so we can consolidate the information.

Good luck!  There's a first time for everything.  We'll all get better at it as we go.

=)