GWD-30-Q7, 8, 12, 22, 23,30

請各位牛人 幫幫呆小妹~tks!

Q7:

There are 11 women and 9 men in a certain club.  If the club is to select a committee of 2 women and 2 men, how many different such committees are possible?

A.          120

B.          720

C.          1,060

D.          1,520

E.          1,980

Q8:

 (圖出不來@@" 有題目在手的牛人們請幫幫忙~)

In the figure shown, two identical squares are inscribed in the rectangle.  If the perimeter of the rectangle is 18√2, then what is the perimeter of each square?

A.          8√2

B.          12

C.          12√2

D.          16

E.          18

Q12:

Working alone at its constant rate, machine K took 3 hours to produce  of the units produced last Friday.  Then machine M started working and the two machines, working simultaneously at their respective constant rates, took 6 hours to produce the rest of the units produced last Friday.  How many hours would it have taken machine M, working alone at its constant rate, to produce all of the units produced last Friday?

A.      8

B.      12

C.      16

D.     24

E.      30

Q22:

 (圖出不來@@" 有題目在手的牛人們請幫幫忙~)

What is the volume of the cube above?

(1)
            The surface area of the cube is 600 square inches.

(2)             The length of diagonal AB is 10√3 inches.

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.

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.

先叩謝了!!

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.

先叩謝了!!

7. select 2 women from 11 women => (11*10)/(2*1)

   select 2 men from 9 men => (9*8)/(2*1)

all together, 11*10*9*8/4 = 1980

8.设左上的那个小三角型的一个直角边是a   由于所有的三角形都是等腰直角 那么长方形的周长可一用12a表示 即12a=18√2

正方形周长就是（4√2）a    得出正方形周长为12

12.

machine K took 3 hours to produce  of the units produced last Friday =>3K=1/4 => K=1/12

Then machine M started working and the two machines, working simultaneously at their respective constant rates, took 6 hours to produce the rest of the units produced last Friday =>6(M+K)=3/4 => M=1/8-K=1/24   

How many hours would it have taken machine M, working alone at its constant rate, to produce all of the units produced last Friday => 1/M=24

22. volume of the cube = a*a*a

surface area = a*a*6 = 600 ,then a=10=>a*a*a=1000

the length of AB = √3a =10√3 , then a=10

23. (0.8)^-5 / (0.4)^-4 = (1/0.4)⁴   /   (1/0.8)⁵  = (0.4/0.8)⁴      /     (1/0.8) =(1/16)  /  (1/0.8)  = 5/64

30.   40miles = 40*5280 feet = 211,200 feet

88f/s * 45*60s = 237,600 feet        因为less than 45mins 所以，路程<237,600      可能大于也可能小于 211，200

88f/s *42*60s= 221,760 feet           因为more than 42mins 所以，路程> 221,760    一定大于211，200  

所以选B

希望能看的懂，加油！！

哇~你真是太厲害了!

謝謝你的詳解~我都會了!