请教GMAT题.What was the percent increase in theaverage (arithme

请教GMAT题.
What was the percent increase in the
average (arithmetic mean) contribution per member of a certain public radio
station from 1985 to 1995
(1) Total contributions by
members increased from $505,210 in 1985 to $1,225,890 in 1995.
(2) The
number of members exactly doubled from 1985 to 1995.
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.
Of the people who attended a workshop,60 percent were teachers and some of the teachers were teachers of language arts.What percent of the people who attended the workshop were teachers of language arts?
(1) 200 people attended the workshop.
(2) 72 of the teachers who attended the workshop were not teachers of language arts.
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.
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.
The positive numbers w,x,y,and z are such that x is 20 percent greater than y,y is 20 percent greater than z,and w is 20 percent less than x.What percent greater than z is w
A.15.2%
B.16.0%
C.20.0%
D.23.2%
E.24.8%

1、选C,那个条件1和2加在一起可以得到结论,
问题中要求得the percent increase in the average contribution per member of=（(Y/B)-（X/A））/(X/A) *100 就要知道4个量：
1、1985年员工总人数A
2、1995年员工总人数B
3、1985年contribution总量X
4、1995年contribution总量Y
条件1给出了X和Y的值
条件2给出了B=2A
带入式子中,发现B时可以消元的,既得答案.
2、选C,依然是两个答案在一起可以解答,根据条件1可知参与的老师一共有200*0.6=120人,根据条件2可知参与的艺术老师有120-72=48人,所以得出结论参与的艺术老师占参与人数的百分比可知48/200答案不用算了.
3、选A,根据题目表述可列式子如下：
X=1.2Y
Y=1.2Z
W=0.8X
所以可知W=1.152Z
这个题其实很容易,不要看到条件多久晕,其实一步一步来就发现不难.
最后再补一句,你这问题真不少,本人要求加给分数昂!