GWD数学中一题求解

carolcai · 发表于 2008-4-27 11:30:00

A photographer
will arrange 6 people of 6 different 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 the people within each row must increase from left to right, and each person 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

这个题目已经出现过好几次了，之前也看过有关求解，但还是不会做，请高人指点啊～多谢

anistonlucky · 发表于 2008-4-27 11:39:00

我选A

xma48215 · 发表于 2008-4-27 11:53:00

用穷举法、I。125 346 II。124 356 III。123 456 IV。134 256 VI。135 246

前三个数代表第一排，后三个数代表第二排。

anistonlucky · 发表于 2008-4-27 11:55:00

楼上的牛牛啊，如果这题改成10个人，还是按那个规律排2排，答案是多少呢？

难道还是列举吗？有没有什么公式或者规律？

xma48215 · 发表于 2008-4-27 11:58:00

这一题是2001年1月份的真题，穷举法我觉得最可靠~具体可以看看CD的及考数学排列组合难题汇编~

carolcai · 发表于 2008-4-27 12:44:00

多谢高人

carolcai · 发表于 2008-4-27 12:45:00

If n is a positive integer and r is the remainder when (n-1)(n+1) is divided by 24, 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 not sufficient.

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

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

D. EACH statement ALONE is sufficient.

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

Answer: C

那这道题有没有好的方法？

GWD数学中一题求解

GWD数学中一题求解

所属分类: GMAT考试

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