三道数学题求解， 谢谢！！

deedeexoxo

Q14:  (怎算都不对）。。。

How many seconds will it take for a car that is traveling at a constant rate of 45 miles per hour to travel a distance of 22 yards?       (1 mile = 1,160 yards)

 

A.      8

B.       9

C.      10

D.      11

E.       12

Answer:

Q17:我所出来是 1/(5+2Ö6) 都不对。

Which of the following is equal to [1/(Ö3 - Ö2)]²?

 

A.      1

B.       5

C.      Ö6

D.      5 - Ö6

E.       5 + 2Ö6

Answer:

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Q18:这个不会做了

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) %

fanstar1987

一、题目应该有问题，因为1mile=1760yards....

fanstar1987

Q17你算错了LZ，完全平方打开中间那一项是减，得出1/(5-2根号6)，然后进行分母有理化上下同时乘以（5+2根号6），选择E

deedeexoxo

谢谢fanstar

有人会第三道题吗？

michael_mei

Q18:

question is about the increased ratio of Price/Earning(P/E).

previous year: P/E

this year: P(1+k%)/E(1+m%),

So the increased ratio is [P(1+k%)/E(1+m%)-P/E]/[P/E]=(1+k%)/(1+m%)-1=(k-m)/(100+m)= [100(k-m)]/(100+m) %, So D is correct.

michael_mei

Q17:

1/(Ö3 - Ö2) = Ö3 + Ö2

[1/(Ö3 - Ö2)]² =(Ö3 + Ö2)²  =5+2Ö6                

  

deedeexoxo

以下是引用michael_mei在2008-6-12 20:20:00的发言：

Q18:

question is about the increased ratio of Price/Earning(P/E).

previous year: P/E

this year: P(1+k%)/E(1+m%),

So the increased ratio is [P(1+k%)/E(1+m%)-P/E]/[P/E]=(1+k%)/(1+m%)-1=(k-m)/(100+m)= [100(k-m)]/(100+m) %, So D is correct.

谢谢！解释得很清楚