1月 jj36－86讨论稿

深海的小美人鱼

以下是引用zhangy在2004-1-6 7:58:00的发言：
69． N is a two-digit number, what’s the tens of n?
a. The tens of 2n =5
b. The tens of 2n=0
小鱼评价：D

B is correct.
AS for a,  n can be 7*or 2*
  

同意。

qunlilin

69． N is a two-digit number, what’s the tens of n?
a. The tens of 2n =5
b. The tens of 2n=0
小鱼评价：D

B is correct.
AS for a,  n can be 7*or 2*

***********************************************************

From condition A: we know that n can be 7* or 2*
From condition B: we know that n can be 5*

Since we can derive different answers from these conditions, should the answer be E ?
conditions are not sufficient to answer the question.

kathy_sd

以下是引用qunlilin在2004-1-6 9:02:00的发言：
From condition A: we know that n can be 7* or 2*
From condition B: we know that n can be 5*

Since we can derive different answers from these conditions, should the answer be E ?
conditions are not sufficient to answer the question.

choose the one that only have one exactly answer!

kathy_sd

以下是引用深海的小美人鱼在2004-1-6 8:04:00的发言：
10,和9是怎么得出来的呢？ 要知道并不是所有的因子相乘啊。

我用笨法子， 当其中一个数为1时，另一个数可以为（1，2，3，4，5，6）， 当其中一个数字为2时候，另一个可以为（3，4，5），当一个数字为3时，另一个可以是（4）， 所以又6+3+1=10种可能 - 1个重复的情况（1*6=6， 2*3=6）所以，一共是9种，对不对啊？

kathy_sd

以下是引用must750在2004-1-6 4:49:00的发言：
85.the gross profit for A is 10 % its selling price,the gross profit for B is 90 % its selling price. A costs three time B. what percent of the total cost of A and B is the profit of A and B combined.

My answer is 7/3

Suppose Price of A is Pa, Price of B is Pb, Cost of A is Ca, Cost of B is Cb,
Profit of A = Pa - Ca = 0.1Pa
=> Pa = Ca/0.9
Profit of B = Pb - Cb = 0.9Pb
=> Pb = Cb/0.1

(the profit of A and B combined)/(total cost of A and B)
= ((Pa-Ca)+(Pb-Cb)) / (Ca+Cb)
=(Pa+Pb)/(Ca+Cb) -1
=(Ca/0.9 + Cb/0.1) / (Ca+Cb) - 1
=(3Cb/0.9 + Cb/0.1) / (3Cb + Cb) -1
=7/3

the answer is 3/7 or 7/3? which is the numerator?

深海的小美人鱼

以下是引用qunlilin在2004-1-6 9:02:00的发言：
69． N is a two-digit number, what’s the tens of n?
a. The tens of 2n =5
b. The tens of 2n=0
小鱼评价：D

B is correct.
AS for a,  n can be 7*or 2*

***********************************************************

From condition A: we know that n can be 7* or 2*
From condition B: we know that n can be 5*

Since we can derive different answers from these conditions, should the answer be E ?
conditions are not sufficient to answer the question.

当2n的十位是0的时候，N只能是5，不能是其他的数字。所以只能是B。

bigcamel

61.L和M驾驶一辆车一同行驶(L和M各行驶一段路程)，平均速度为90mile/ hour.。求L的平均速度是否大于80？
（1）M的平均速度大于100 （2）M的时间大于L的时间
作者答案及思路：C
小鱼评价： 不同意 没有交代两人的行驶距离

答案应该是C

bigcamel

64． The mean of x, y, z is 10, xi. 9
ii. 10
iii. 11
a.I only
b. II only
c. III only
d. I and III
e. I, II, and III
小鱼评价： 题目有问题，应该是z-x=3。否则 只能得 9。9。12 和8。8。11 和条件相左

应该是B 8.5  10 11.5

深海的小美人鱼

以下是引用bigcamel在2004-1-6 11:00:00的发言：
61.L和M驾驶一辆车一同行驶(L和M各行驶一段路程)，平均速度为90mile/ hour.。求L的平均速度是否大于80？
（1）M的平均速度大于100 （2）M的时间大于L的时间
作者答案及思路：C
小鱼评价： 不同意 没有交代两人的行驶距离

答案应该是C

讲讲为什么嘛

must750

以下是引用深海的小美人鱼在2004-1-6 8:04:00的发言：
10,和9是怎么得出来的呢？ 要知道并不是所有的因子相乘啊。

p=2, q=5 => p*q = 10
p=3, q=3 => p*q = 9