求大神解答GWD数学题，小女子拜谢

shangsi

Q16:
In the sequence of nonzero numbers t1, t2, t3, …, tn, …, tn+1 = tn / 2 for all positive integers n.  What is the value of t5?
(1)          t3 = 1/4
(2)          t1 - t5 = 15/16
               
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
这个有点没看懂，网上也搜不到解释

Q20:

Of the students in a certain school, 15 percent are enrolled in an art class and 10 percent are enrolled in a music class.  What percent of the students in the school are enrolled in neither an art class nor a music class?

(1)   2/3 of the students who are enrolled in an art class are also enrolled in a music class.

(2)     There are more than 100 students in the school.

                                                                                                                              

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.
我选E啊

Q26:

If n = 3k, is k an integer?

(1)     n is an integer.

(2)     n/6 is an integer.

                                                                                                                              

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.

Q34:

If Antonio bought two half-gallon cartons of ice cream during a special sale, what percent of the total regular price of the two cartons did he save?

(1)   Antonio paid the regular price for the first carton and received the second carton for half the regular price.

(2)   The regular price of the ice cream Antonio bought was $4.00 per half-gallon carton.

                                                                                                                              

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.

谢谢啦！！！！

elsachialee

Q16:
In the sequence of nonzero numbers t1, t2, t3, …, tn, …, tn+1 = tn / 2 for all positive integers n.  What is the value of t5?
(1)          t3 = 1/4
(2)          t1 - t5 = 15/16

tn+1=tn/2

所以，t2=t1/2, t3=t2/2=t1/4, t4=t3/2=t2/4=t1/8...tn=t1/(2^n-1)
A: t3=1/4, t1=1, t5=t1/2^4=1/2^4 sufficient
B: t1 - t5 = 15/16, 1-t5=15/16, t5=1/16 sufficient

elsachialee

Of the students in a certain school, 15 percent are enrolled in an art class and 10 percent are enrolled in a music class.  What percent of the students in the school are enrolled in neither an art class nor a music class?
(1)   2/3 of the students who are enrolled in an art class are also enrolled in a music class.
(2)     There are more than 100 students in the school.

你这个你画个图，一个框，代表所有学生。
框里头两个圈，左右，有相交。左边表示15％的Art，右边是10％的music, A里头说2／3 参加美术的学生，也参加了音乐，所以中间相交的就是2／3*15％，那么整个圈子外面就是，1－（10％＋15％－2／3*15％） sufficient

非牛，参与讨乱。

elsachialee

If n = 3k, is k an integer?
(1)     n is an integer.
(2)     n/6 is an integer.

这种题目，我一般就举例。。。比较笨的办法。

N是整数，所以。。1 2 3 4 5 6.。。显然k可能是整数，也可能不是。不充分
n／6是整数，所以，n是6 12 36 那么可以被3整除，所以k是整数，充分。。。

elsachialee

If Antonio bought two half-gallon cartons of ice cream during a special sale, what percent of the total regular price of the two cartons did he save?
(1)   Antonio paid the regular price for the first carton and received the second carton for half the regular price.
(2)   The regular price of the ice cream Antonio bought was $4.00 per half-gallon carton.
这个你是不是没看懂题目阿。。。翻译成中文，肯定会的阿。。。
说一个A的小朋友在特价的时候去买了2个冰淇淋。问节省的钱比原价是多少？
说第一个原价，第二个半价
原价本来是4刀一个。
很明显第一个就充分，第二个无关。
（1－1.5／2）＊100％

我太热情了，有木有。。。。

samlywt2013

DDDDDDDDDDDDDDDDD

shangsi

elsachialee 发表于 2013-9-28 16:22
If Antonio bought two half-gallon cartons of ice cream during a special sale, what percent of the to ...

谢谢啦！！！看完解释顿时恍然大悟！！拜谢！