请教GWD数学若干题. 28日考

请教:

1)PREP模考才640分,很急很急.28日考试!

2)GWD数学很多不会的.有朋友愿意帮忙吗?
 GWD-3-15/18

 GWD5-3

GWD7-3

GWD8-28

GWD15-2

GWD16-9

GWD17-9

GWD18-9/22

GWD19-32

GWD23-14

GWD24-16/26

GWD25-10/13/23/2932

GWD26-7/31

GWD30-9

 GWD-3-15/18

Q15:

If n and k are positive integers, is n/k an even integer?

(1)     n is divisible by 8.

(2)     k is divisible by 4.

这题选E. 如果条件给的是N和K分别能整除的最大整数是8,4,则选C.

举例: N=8,K=16

A.     k/m %

B.     (k-m) %

C.     [100(k-m)]/(100+k) %

D.     [100(k-m)]/(100+m) %

E.      [100(k-m)]/(100+k+m) %

题目问的是ratio of price per share to earnings per share 增加了多少.设单价为P, 赢利为M.

则增加的RATIO 等于 [P(1+K%)/M(1+M%)-P/M]除以P/M,化简则为(1+K%)/(1+M%)-1.因问的是PERCENT的增加,则最后化简为答案D

GWD5-3

If a committee of 3 people is to be selected from among 5 married couples so that the committee does not include two people who are married to each other, how many such committees are possible?

A.     20

B.     40

C.     50

D.     80

E.      120

C(3,10)-C(1,5)C(1,8)=80

GWD7-3

Material A costs $3 per kilogram, and material B costs $5 per kilogram.  If 10 kilograms of material K consists of x kilograms of material A and y kilograms of material B, is x > y?

(1)     y > 4

(2)     The cost of the 10 kilograms of material K is less than $40.

根据条件1,当Y=5时,X=5,当Y>5时,X<Y.故不成立

根据条件2可列出式子 3X+5Y<40, 有因为X+Y=10,将X=10-Y代入式子中,可得Y<5,则X>Y.成立

GWD8-28

A car traveling at a certain constant speed takes 2 seconds longer to travel 1 kilometer than it would take to travel 1 kilometer at 75 kilometers per hour.  At what speed, in kilometers per hour, is the car traveling?

A.     71.5

B.     72

C.     72.5

D.     73

E.      73.5

设速度为X千米每小时,则有等式 1/X-2/3600=1/75,解出X=72.

GWD15-2

第一页就有这题的解答,画图即可

GWD16-9

Q9:

If xyz > 0, is xy²z³ < 0 ?

(1)     y < 0

(2)     x > 0

根据条件1,Y<0,则XZ<O,因Y^2>0,则XY^2Z^3<0

根据条件2,不能判断.

选A

GWD17-9

Q9:

Is x greater than y ?

(1)     x – y² > 0

(2)     xy < 0

根据条件1,X>Y^2,并不能判断X,Y谁大谁小,要考虑X,Y为小于1时的情况

根据条件2,得出X,Y一正一负,不能判断出谁正谁负.

两个条件结合,因为X>Y^2,则X为正，Y为负,则X>Y. 选C

GWD26-Q7:

If y is an integer and y = ½x½ + x, is y = 0?

(1)   x < 0

(2)     y < 1

26-Q31:

One kilogram of a certain coffee blend consists of x kilogram of type I coffee and y kilogram of type II coffee.  The cost of the blend is C dollars per kilogram, where C = 6.5x + 8.5y.  Is x < 0.8?

(1)
            y > 0.15

(2)  C ≥ 7.30

接着来.请大家帮忙.

GWD25-29

Q29.

if X>1 and Y>1, is X<Y?

(1) X^2/(XY+X)<1