求助GWD30的数学题

Q13:

If x + y is an integer, is y an integer?

(1)     x – y is an integer.

(2)     x + 2y 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.

B

In the rectangular coordinate system, points (4, 0) and (– 4, 0) both lie on circle C.  What is the maximum possible value of the radius of C ?

A.        2

B.        4

C.        8

D.     16

E.      There is no finite maximum value.

E

Q30:

A train traveled from station X to station Y at a constant speed of 88 feet per second.  Is the distance that the train traveled from station X to Station Y greater than 40 miles?    (1 mile = 5,280 feet)

(1)   It took less than 45 minutes for the train to travel from station X to Station Y.

(2) It took more than 42 minutes for the train to travel from station X to Station 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.

B

Q34:

A certain company that sells only cars and trucks reported that revenues from car sales in 1997 were down 11 percent from 1996 and revenues from truck sales in 1997 were up 7 percent from 1996.  If total revenues from car sales and truck sales in 1997 were up 1 percent from 1996, what is the ratio of revenue from car sales in 1996 to revenue from truck sales in 1996?

A.    1 : 2

B.    4 : 5

C.    1 : 1

D.    3 : 2

E.    5 : 3

A

Q13

条件1：x+y is an integer,x-y=x+y-2y, so 2y is an integer.

条件2：x+2y=x+y+y,x+y is an integer, and x+2y is an integer,so  y is an integer.

Q30:If the distance is 40 mile, the train will cost 40 minutes.

5280*40/(88*60)=40

条件1，无法得出结论

条件2，得出距离一定大于40 miles.

so B

Q34：

令car的revenue是c,truck的revenue是t

(89%*t+107%*t)/(c+t)=101%

6t=12c

c/t=1/2

A