求助一道GWD 数学的题目~~~GWD29 Q13

viridian · 发表于 2011-6-21 21:05:39

For any positive integer x, the 2-height of x is defined to be the greatest nonnegative integer n such that 2n is a factor of x. If k and m are positive integers, is the 2-height of k greater than the 2-height of m ?
(1)    k > m
(2)   k/m is an even integer.

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.

答案 B

Q22:

Four extra-large sandwiches of exactly the same size were ordered for m students, where m > 4. Three of the sandwiches were evenly divided among the students. Since 4 students did not want any of the fourth sandwich, it was evenly divided among the remaining students. If Carol ate one piece from each of the four sandwiches, the amount of sandwich that she ate would be what fraction of a whole extra-large sandwich?

A. (m+4)/[m(m-4)]

B. (2m-4)/[m(m-4)]

C. (4m-4)/[m(m-4)]

D. (4m-8)/[m(m-4)]

E. (4m-12)/[m(m-4)]

答案E

这题看不懂....= =

viridian · 发表于 2011-6-22 13:56:51

UPUP~~~

mlhxzfq · 发表于 2011-7-13 20:35:46

2-height 题是GMAT数学部分常考的一个题型。因为题中会给出一个关于2-height的定义, 所以G友通常称之为2-height题。

举个例子吧，40=2*2*2*5，即2的三次方乘以5，3就是2-height 的值，再如12=2*2*3，即2的二次方乘以3，所以2就是2-height 的值。
总的来说，就是把一个整数分解成质数的乘积，其中2的幂就是2-height 的值。

k>m 的条件，很明显不行
k/m为偶数，即k/m=2n, 因此这个条件可以断定k比m多一个2，所以k的2-height>m的2-height

Q22. 前三个sandwiches被平均分给所有学生，每个sandwiches即为1/m
最后一个sandwich，有四个学生不要，则为1/(m-4)
Carol 取每个sandwich的一部分,并需要计算他取的总数是一整个sandwich的几分之几，即为[3/m + 1/(m-4)]/1，最后得答案E

求助一道GWD 数学的题目~~~GWD29 Q13

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