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标题: gwd 数学问题跪求大牛指导…… [打印本页]

作者: 无忧小乐 时间: 2012-5-4 23:46
标题: gwd 数学问题跪求大牛指导……
Lists S and T consist of the same number of positive integers. Is the median of the integers in S greater than the average (arithmetic mean) of the integers in T?

(1)The integers in S are consecutive even integers, and the integers in T are consecutive odd integers.

(2) The sum of the integers in S is greater than the sum of the integers in T.

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.
标准答案为c表示不理解……

作者: momo101 时间: 2012-5-5 09:36

Lists S and T consist of the same number of positive integers. Is the median of the integers in S greater than the average (arithmetic mean) of the integers in T?

(1)The integers in S are consecutive even integers, and the integers in T are consecutive odd integers.

(2) The sum of the integers in S is greater than the sum of the integers in T.

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.
标准答案为c表示不理解……

-- by 会员无忧小乐 (2012/5/4 23:46:30)

题目：S和T这2个集合里有相同数量的的正数，S的中位数比T的平均数大吗？
1:S里都是连续偶数，T里是连续奇数。2：S的和大于T的和

先看1，很容易举反例。s(2,4) T(99,100)和S（100，102）T（1，3）结果不同
再看2，再举反例，S（100，5，5）T（1，1，1）和S（100，5，5），T（20，20，20）结果不能确定
再看C：规范的解法是。。因为S是连续偶数，所以S的中位数等于S的平均数，集合的平均数决定于元素的数量和集合的和，已知S的和大于T的和，数量一样，所以可知S的平均数大于T，即中位数大于T的平均数
建议用排除法。排了AB，在多代几个极端值到C，能算出来就一般是对的。。

作者: jhc2010 时间: 2012-5-6 17:41
S： 8 6 4 2 0 -2
T: 7 5 3 1 -1
这个怎么解释？

作者: jhc2010 时间: 2012-5-6 17:45
题目只说正整数数量相等，没说所有整数的数量相等啊！

作者: jhc2010 时间: 2012-5-6 17:48
哦，我错了，T和S只包含正整数。。。

作者: 无忧小乐 时间: 2012-5-9 15:25
我真的很讨厌gwd~对了没有安全感~错了也经常不知道错在哪~~谢谢大家帮助~~~我自己在研究研究罢了~~~

作者: Apan0988 时间: 2018-10-2 12:15

无忧小乐发表于 2012-5-9 15:25
我真的很讨厌gwd~对了没有安全感~错了也经常不知道错在哪~~谢谢大家帮助~~~我自己在研究研究罢了~~~ ...

对了你就噜一管啊，这样就宽心了不少。

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