今天刚做GWD1的数学,居然错了9题,但是看完后还是不知其解,请大家帮忙

Q34:

In the xy-plane, what is the slope of line l?

(1)     Line l dose not intersect the line with equation y = 1 - x.

(2)     Line l intersects the line with equation y = x – 1.

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.

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Q30:

The total cost of an office dinner was shared equally by k of the n employees who attended the dinner.  What was the total cost of the dinner?

(1)     Each of the k employees who shared the cost of the dinner paid $19.

(2)   If the total cost of the dinner had been shared equally by k + 1 of the n employees who attended the dinner, each of the k + 1 employees would have paid $18.

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.

Q26:

If the units digit of the three-digit positive integer k is nonzero, what is the tens digit of k?

(1)     The tens digit of k + 9 is 3.

(2)     The tens digit of k + 4 is 2.

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.

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Q19:

Each of the 30 boxes in a certain shipment weighs either 10 pounds or 20 pounds, and average (arithmetic mean) weight of the boxes in the shipment is 18 pounds.  If the average weight of the boxes in the shipment is to be reduced to 14 pounds by removing some of the 20-pound boxes, how many 20-pound boxes must be removed?

A.     4

B.     6

C.     10

D.     20

E.      24

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Q15:

If p is the product of the integers from 1 to 30, inclusive, what is the greatest integer k for which 3^k is a factor of p?

A.     10

B.     12

C.     14

D.     16

E.      18

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Q16:

If x and y are positive, is x³ > y?

(1)      > y

(2)     x > y

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.

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Q10:

What is the value of (x - y)⁴?

(1)     The product of x and y is 7.

(2)     x and y are integers.

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.

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Q7:

A certain university will select 1 of 7 candidates eligible to fill a position in the mathematics department and 2 of 10 candidates eligible to fill 2 identical positions in the computer science department.  If none of the candidates is eligible for a position in both departments, how many different sets of 3 candidates are there to fill the 3 positions?

A.     42

B.     70

C.     140

D.     165

E.      315

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Q2:

If 2 different representatives are to be selected at random from a group of 10 employees and if p is the probability that both representatives selected will be women, is p > ?

(1)     More than  of the 10 employees are women.

(2)     The probability that both representatives selected will be men is less than .

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、1--〉直线肯定和y=-x+1平行 2 不能得出斜率， 所以我选A

2、综合1、2得出 19k=18(k+1)，可以得出k,自然总的价钱也就知道了，所以我选C

3、1--> 十位数肯定是3-1=2，因为任何不为零的数+9都会进一位。

4、10x+20y=18x30; 10x+20(y-n)=18x30-20n=14x(30-n)-->n=20

5,1-30中有3这个之因子的数连乘3的幂是14，所以选择C