GWD数学题请指教，谢啦

GWD10--Q10

A certain quantity is measured on two different scales, the R-scale and the S-scale, that related linearly. Measurements on the R-scale of 6 and 24 correspond measurements on the S-scale of 30and 60, respectively.What measurement on the R-scale correspond to a measurement of 100 on the S-scale?

A.20

B.36

C.48

D.60

E.84

答案是C

GWD3--Q33

A photographer will arrange 6 people of 6different heights for photograph by placing them in two rows of three so that each person in the first row is standing in front of someone in the second row, The heights of people within each row must increase from left to right,and each in the second row must be taller than the person standing in front of him or her. How many such arrangements of the 6 people are possible?

A.5

B.6

C.9

D.24

E.36

答案是A

GWD7--Q28

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 apend will be equal to half the amount that he spends this year

A1/r+2

B1/2r+2

C1/3r+2

D1/r+3

E1/2r+3

答案是E

GWD4--Q18

What is the total value of Company H's stock?

(1)Investor P owns 1/4 of the shares of Company H's total wtock

(2)The total value of Investor Q's shares of Company H's stock is $16,000

答案是D，可我觉得是E。因为题目没有说这个公司只有这两个投资者

太困惑了。请指教。谢谢

1. suppose S= aR+b

    30=6a+b   60=24a+b a=30/18 = 5/3 b= 20    S=5/3R+20  S=100=> R= 48

   很像Celcius 和Farenheit的转换

2. A只能站row 1, Row1可以是 ABC ABD ABE ACD ACE

                 对应Row2   DEF CEF CDF BEF BDF

列举出来的 定了Row1 Row2也只能有1种排法

3。x fraction. Total Income , I

    xI(1+r) = 1/2*(1-x)I  => x= 1/(3+2r)

4. 我也觉得是E 应该不会是D啦

如果只有两个，能算出来,也是应该选C的，也不是D，所以八成搞错了

对 P和Q无关嘛

第2题的意思是只有一种排列方法吗？可我觉得至少有两种

第一种是row1:ABC,row2EF

第二种是row1:ACE,row2:BDF

其他的就不知道了，答案是5种，我觉得很诧异，O(∩_∩)O~

 DEF CEF CDF BEF BDF

５种