几道GWD数学题求教大神，感激不尽~~

whisper15

Aphotographer will arrange 6 people of 6 different heights for photograph byplacing them in two rows of three so that each person in the first row isstanding in front of someone in the second row. The heights of the people within each row must increase from left toright, and each person in the second row must be taller than the personstanding in front of him or her.  Howmany such arrangements of the 6 people are possible?

A.    5

B.     6

C.   9

D.   24

E.    36

这个除了列举出来，还可以怎么算呀。。。

InJune 1989, what was the ratio of the number of sales transactions made bySalesperson X to the number of sales transactions made by Salesperson Y?

(1)   In June 1989, Salesperson X made 50 percentmore sales transactions than Salesperson Y did in May 1989.

(2)   In June 1989, Salesperson Y made 25 percentmore sales transactions than in May 1989.

                  

A.Statement (1) ALONE is sufficient, but statement (2) alone is notsufficient.

B. Statement (2) ALONE issufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER aresufficient, but NEITHER statement ALONE is sufficient.

D.EACH statement ALONE is sufficient.

E.Statements (1) and (2) TOGETHER are NOT sufficient.

为什么不是E。。。不是5月的也被算在里面了嘛。。。

If M is the least common multiple of90, 196, and 300, which of the following is NOT a factor of M?

A.    600

B.     700

C.   900

D.   2,100

E.    4,900

这个除了把最小公倍数求出来，然后一个一个除还有没有别的办法啊。。。

Ifn is a positive integer and r is the remainder when (n-1)(n+1) is divided by24, what is the value of r?

(1)   2 is not a factor of n.

(2)   3 is not a factor of n.

                  

A.Statement (1) ALONE is sufficient, but statement (2) alone is notsufficient.

B.Statement (2) ALONE is sufficient, but statement (1) alone is notsufficient.

C. BOTH statements TOGETHER aresufficient, but NEITHER statement ALONE is sufficient.

D.EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHERare NOT sufficient.

完全不会。。。


感激不尽！！！

tzshasha

第一题 照相问题。我记得高中排列组合课 这种题目比较特殊，没有公式能计算出来，需要一一列举。所幸只有6个人，按个子高矮123456排列的话，1肯定排在第一排第一位，6固定在第二排最后一位。剩下的四个再组合。答案是A？

tzshasha

第二题。比较6月X跟Y的销售RATIO问题。答案A？我觉得就条件1就可以算出来了 X=(1+50%)Y。条件2是销售员Y本人6月与5月的比较吧。。。。。

tzshasha

最后一题，我个人觉得答案是C，得出的R=0. 不过具体的在线等牛人解答~~~~~~~~

whisper15

tzshasha 发表于 2015-3-20 17:55
第二题。比较6月X跟Y的销售RATIO问题。答案A？我觉得就条件1就可以算出来了 X=(1+50%)Y。条件2是销售员Y本 ...

这个答案是C哦

lashi4s

whisper15 发表于 2015-3-20 18:46
这个答案是C哦

同意第二题答案是C

lashi4s

最后一题，
条件一，可得出，n-1、n+1 都是2的倍数，然而n-1、n+1是连续两个2的倍数，所以若n-1除以2得a，则n+1除以2 得a+1, a和a+1必有一个可以除以2 ，所以(n-1)(n+1)可以整除8
条件二，n-1、n、n+1 为连续的三个数，必有一个可以整除3.

条件一+条件二得出(n-1)(n+1)可整除24

tzshasha

lashi4s 发表于 2015-3-20 20:44
最后一题，
条件一，可得出，n-1、n+1 都是2的倍数，然而n-1、n+1是连续两个2的倍数，所以若n-1除以2得a， ...

太厉害了！！但是第二题为什么选C呢？

lashi4s

tzshasha 发表于 2015-3-20 22:02
太厉害了！！但是第二题为什么选C呢？

你肯定没好好看条件一，我的解释和楼上那个人一样

Lauraienglish

设y5月是x，由1得x6月是1.5x；由2得y6月是1.25x；所以才能知道x6月比y6月是1.5x/1.25x=1.2