GWD 4-16,19,20

abiding

下面几题都不会做，诚心请教!

Q16:

In the sequence of nonzero numbers t₁, t₂, t₃, …, t_n, …, t_n+1 = t_n / 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.

Q19:

Which of the following is equal to (2¹² – 2⁶) / (2⁶ – 2³)?

 

A.     2⁶ + 2³

B.     2⁶ - 2³

C.     2⁹

D.     2³

E.      2

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.

hitlzc

4-19这个考察的是因式分解。

 (2¹² – 2⁶) ＝ (2⁶ – 2³)（
            2⁶ + 2^3）

hitlzc

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.

（1）显然是单独充分的。

（2)根据题干t5=t4/2=2t3/2=8t1/2，与条件（2）可解出t5

所以选D

hitlzc

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.

选A

1-15%-10%+15%*2/3

abiding

Thank you so much!!!

diamondivy

小妹有个疑问  

(1)   条件是说
                     有2/3 art class 的学生也有到
                music class，

那不就是只能推出一部分的交集人数而已？

因为题目并没有说   music class 里有多少比例的人也有到
                art class

 

还请各位多多指点一下，谢谢！

朵夫

  我也是有同感啊 这个2/3 art class 的学生也有到
            music class  不等于说是 所有即选了 art  又选了 music 的比例嘛

这个题目怎么沉了3年了  NN们来澄清一下呐