老题已经解决了，又加了新的prep数学题求教

paulfrank11

up一下，又有新题了

paulfrank11

太感谢楼上的解答了，完全明白了

albertwl

d/c < f/p   --->  (f-b)/(p-a) < f/p --->  fp-bp<fp-fa ---> bp > fa ---> b/a > f/p

b/f>50%;c/p>50%  --->  b/f+c/p>1  --->  (bp+cf)/fp>1 ---> bp+fp-af >fp ---> bp>fa ---> b/a > f/p

paulfrank11

谢谢版主和热心人的解答，豁然开朗！

可是还是有问题，通过那几个不等式怎么判断出 b/a是不是大于F/P呢？

[此贴子已经被作者于2006-12-5 9:37:49编辑过]

albertwl

感谢斑竹画此绝妙好表，使解题思路豁然开朗

mymengming

1)At a dinner party, 5 people are to be seated around a circular table. Two seating arrangements are considered different only when the positiions of the people are different relative to each other. What is the total number of different possible seating arragements for the group?

答案是24，我知道这道题很简单，但是排列组合是弱项，请大家帮助解释一下，谢谢

环形排列与直线排列相比，就相当于少了一个元素。所以可以先求直线排列，再求圆形排列

直线排列是P(5,5)

环形排列就是P（4，4）

2）Data sufficiency的题

Each employee of company Z is an employee of either Division X or Division Y, but not both. If each division has some part-time employees, is the ratio of the number of full-time employees to the number of part-time employees greater for Division X than for company Z?

条件1: The ratio of the number of full-time employees to the number of part-time employees is less for Division Y than for company Z.

条件2: More than half of the full-time employees of

 company Z are employees of Division X, and more than half of the part-time employees of company Z are employees of Division Y.

答案是 D 这道题我读晕了，希望会的好心人给个解释

	X	Y
P	a	c	P
F	b	d	F
	X	Y

 

 

问题问的是b/a> F/P               p=a+c          f=b+d

(1)d/c<f/p

(2)b/f>50%        c/p>50%

 

cmbc168

P44也可以.碰到圆圈坐人,相应减少一个人进行排列即可.

遥远的绿洲

1 假设A B C D E 5个人则自由组合的排列方法有P55=5*4*3*2*1=120种 而对应其中每一种 假设该种排列为 A B C D E,则 B C D E A,  C D E A B, D E A B C, E A B C D在题目看来都是一样的 因此120/5 就是答案了

马上下班了，只有时间看1题了 呵呵，有时间再帮你看后面一题

paulfrank11

新题：

全部都解决拉，谢谢，哈！

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老题

1)

At a dinner party, 5 people are to be seated around a circular table. Two seating arrangements are considered different only when the positiions of the people are different relative to each other. What is the total number of different possible seating arragements for the group?

答案是24，我知道这道题很简单，但是排列组合是弱项，请大家帮助解释一下，谢谢

 

2）Data sufficiency的题

Each employee of company Z is an employee of either Division X or Division Y, but not both. If each division has some part-time employees, is the ratio of the number of full-time employees to the number of part-time employees greater for Division X than for company Z?

条件1: The ratio of the number of full-time employees to the number of part-time employees is less for Division Y than for company Z.

条件2: More than half of the full-time employees fo company Z are employees of Division X, and more than half of the part-time employees of company Z are employees of Division Y.

答案是 D 这道题我读晕了，希望会的好心人给个解释

[此贴子已经被作者于2006-12-7 4:03:26编辑过]