[求助]4道没思路的gwd数学题(11日新加了1道GWD-TN-7的题目)

red_hat

因为我下载的是TN24,所以也不知道相应的GWD的第几题，无法搜索功能了

还请大家见谅！

谢谢！

1:

A certain club has 20 members.  What is the ratio of the member of 5-member committees that can be formed from the members of the club to the number of 4-member committees that can be formed from the members of the club?

A.    16 to 1

B.     15 to 1

C.     16 to 5

D.    15 to 6

E.     5 to 4

Answer:

2:

Last year the price per share of Stock X increased by k percent and the earnings per share of Stock X increased by m percent, where k is greater than m.  By what percent did the ratio of price per share to earnings per share increase, in terms of k and m?

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) %

Answer:

3:

Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day.  If r percent of the store’s revenues from newspaper sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper B, which of the following expresses r in terms of p?

A.    100p / (125 – p)

B.     150p / (250 – p)

C.     300p / (375 – p)

D.    400p / (500 – p)

E.     500p / (625 – p)

Answer:

[此贴子已经被作者于2009-6-11 21:21:30编辑过]

syfins

1、C

C20 5/C20 4

azh826

2. 假设第一年的价格和收入分别为 P1, E1;第二年的价格和收入分别为P2, E2.

根据题意,P2=(1+k%)P1, E2=(1+m%)E1，因此P2/E2=(1+k%)P1/(1+m%)E1

因此(P2/E2-P1/E1)/(P1/E1)=(k-m)/(100+m)= [100(k – m)] / (100 + m) %，选D

azh826

3. Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day.  If r percent of the store’s revenues from newspaper sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper A, which of the following expresses r in terms of p?

我记得题目中有一个B应该是A（标了红色），这样才可解出答案，LZ可以再查一下。

设A,B为售出的报纸数量，

根据题意：
        卖出A占所有的数量百分比为p，因此卖出B占所有的数量百分比为(100-p)

A与B的单价比=1:1.25=4:5，因此A的收入设为4p，B的收入则为5(100-p)

根据题意：卖出A占所有的收入百分比为r，因此4p/(4p+5(100-p))=r/100，r=400p/(500-p)，选D

red_hat

谢谢啊！！

第一题可能我理解错了,我算的是

(C20 5 * C 15 5* C 10 5 ) / (C 20 4 * C 16 4 * C 12 4 * C 8 4)

第二题搞懂了～

第三题可能是我下载的那个版本不好～

 总之谢谢大家

[此贴子已经被作者于2009-6-10 9:23:34编辑过]

red_hat

11日新加了1道GWD-TN-7的题目

还是不知道对应GWD多少题,只能顺着我自己的顺序了!不好意思啊!

This year Henry will save a certain amount of his income, and he will spend the rest.  Next year Henry will have no income, but for each dollar that he saves this year, he will have 1 + r dollars available to spend.  In terms of r, what fraction of his income should Henry save this year so that next year the amount he was available to spend will be equal to half the amount that he spends this year?

(A)1/(r+2)

(B)1/(2r+2)

(C)1/(3r+2)

(D)1/(r+3)

(E)1/(2r+3)

这道题不是很懂在问什么，我选了B.答案是E

This year Henry will save a certain amount of his income, and he will spend the rest.  Next year Henry will have no income, but for each dollar that he saves this year, he will have 1 + r dollars available to spend.  In terms of r, what fraction of his income should Henry save this year so that next year the amount he was available to spend will be equal to half the amount that he spends this year?

(A)1/(r+2)

(B)1/(2r+2)

(C)1/(3r+2)

(D)1/(r+3)

(E)1/(2r+3)

这道题不是很懂在问什么，我选了B.答案是E

[此贴子已经被作者于2009-6-11 21:40:13编辑过]

red_hat

谢谢各位高手啦！

red_hat

不知为何。。

加大字号就自动DOUBLE了?

怎么回是？

[此贴子已经被作者于2009-6-11 21:34:06编辑过]

red_hat

figure it out

save this year: n

available next year: n(r+1)

spend this year: 2n(r+1)

income this year: n+2n(r+1)

fraction n/ [n+2n(r+1)] => 1/(2r+3)

thus, choose E