[求助]GWD31套数学讨论:11-14

xin861123 · 发表于 2008-4-10 19:12:00

各位战友，小弟在网上找了许久也没有看到GWD31套数学的讨论，很多都是讨论VERBAL的，但数学里很多题目知道答案却还是不知道怎么做，（过程！！）想在此向给位高手求救！！谢谢了~~

Q5:

The sides of a square region, measured to the nearest centimeters, are 6 centimeters long. The least possible value of the actual area of the square region is

A. 36.00 sq cm

B. 35.00 sq cm

C. 33.75 sq cm

D. 30.25 sq cm

E. 25.00 sq cm

Answer: D

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Q13:

On a certain day, Tim invested $1,000 at 10 percent annual interest, compounded annually, and Lana invested $2,000 at 5 percent annual interest, compounded annually. The total amount of interest earned by Tim’s investment in the first 2 years was how much greater than the total amount of interest earned by Lana’s investment in the first 2 years?

A. $5

B. $15

C. $50

D. $100

E. $105

Answer: A

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13-Q35:

Stations X and Y are connected by two separate, straight, parallel rail lines that are 250 miles long. Train P and train Q simultaneously left Station X and Station Y, respectively, and each train traveled to the other’s point of departure. The two trains passed each other after traveling for 2 hours. When the two trains passed, which train was nearer to its destination?

(1) At the time when the two trains passed, train P had averaged a speed of 70 miles per hour.

(2) Train Q averaged a speed of 55 miles per hour for the entire trip.

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.

Answer: A

12-Q18:

The function f is defined by f(x) = √x – 10 for all positive numbers x. If u = f(t) for some positive numbers t and u. What is t in terms of u?

A. √(u+10)

B. (√u + 10)²

C. √(u²+10)

D. (u + 10)²

E. (u² + 10)²

Answer: A

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12-Q30:

M = {-6, -5, -4, -3, -2}

T = {-2, -1, 0, 1, 2, 3}

If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T above, what is the probability that the product of the two integers will be negative?

A. 0

B. 1/3

C. 2/5

D. 1/2

E. 3/5

Answer: D

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12-Q32:

Seven different numbers are selected from the integers 1 to 100, and each number is divided by 7. What is the sum of the remainders?

(1) The range of the seven remainders is 6.

(2) The seven numbers selected are consecutive 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.

Answer: B

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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.

Answer: A

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14-Q17:

If x, y, and k are positive numbers such that (
x/x+y)(10) + (y/x+y )(20) = k and if x < y, which of the following could be the value of k?

A. 10

B. 12

C. 15

D. 18

E. 30

Answer: D

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[此贴子已经被作者于2008-4-10 19:19:01编辑过]

ChrisCong · 发表于 2008-4-11 09:11:00

Q5:四个字:四舍五入,所以6,最小的数就是5.5进上去的,so...

Q13:就是算,1000*1.1*1.1=1210 2000*1.01*1.05=1205 差是5,so...

13-q35, 一点：平均速度就是路程除以时间，和是否匀速是没关系的．

　　　　１，里根据７０，可以算出他２小是走了１４０，谁离终点近，一目了然．

　　　　２，５５的全程平均速度完全不make sense．可以想象一个极端的例子，他既可以一开始慢得和蜗牛一样，然后相遇后突然爆发，也可以一开始快得要死，相遇后慢下来．不需要定量计算，有时候这么定性的一想，就可以了．

Q18,我看来看去都是D,不理解啊不理解.

Q30,观察:上面全负的,必须乘个正数积才是负的,下面6个数,3个正的,所以1/2

Q32,1,注意,是余数的RANGE,不是这7个数.如果是这7个数,那也证明是连续的,和2一样了.那就对了.要看清楚.

2,连续7个数被7除,余数必然是,0,1,2,3,4,5,6 只是从哪一个开始而已嘛.所以是对的.

最后一题,把原来的式子小变一下,然后观察.变成:

10+10(y/x+y)=k,然后把目光集中在这个式子上y/(x+y),由于x,y是正数,所以他必然小于y/y=1

所以可以知道k<20,接着,继续观察,利用x<y这个条件,发现,当x=y的时候,k=15,但实际是x<y,所以k>15

所以15<k<20,选18

晚饭后精力很涣散,不对的地方,多包含

dearo · 发表于 2015-9-6 05:44:07

ChrisCong 发表于 2008-4-11 09:11
Q5:四个字:四舍五入,所以6,最小的数就是5.5进上去的,so...Q13:就是算,1000*1.1*1.1=1210   2000* ...

Mark一下！

[求助]GWD31套数学讨论:11-14

[求助]GWD31套数学讨论:11-14

所属分类: GMAT考试

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