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标题: 数学PP请教2 [打印本页]

作者: 马尔代夫 时间: 2006-7-11 16:50
标题: 数学PP请教2
[attachimg]48509[/attachimg]
这道题算出来是X>6啊，不知道哪里错了？

作者: kallyli 时间: 2006-7-11 17:48
1,3,8.12
if 6<x<8, (24+x)/5=x, x=6, we may know if the median is greater than the average
if x>=8, it's not certain(the following will give the reason), so 1 is not sufficent
from 2 we can get that x is larger than 8, (x+24)/5=8, x=16, so if x is larger than 16 ,median is larger than average, if 8<x<16, median is smaller than average, 2 is not suffcient
and the two together are not suffcient
so E is right

作者: zhengxian 时间: 2006-7-12 03:42

奇怪了，

我怎么觉得（1），（2）式都是X>6,

并且X分别代入6。2， 7， 8， 10， 13 都得出中数大于平均数嘛。

是哪里出了错内？

作者: 马尔代夫 时间: 2006-7-12 11:36

以下是引用kallyli在2006-7-11 17:48:00的发言：
1,3,8.12
if 6<x<8, (24+x)/5=x, x=6, we may know if the median is greater than the average
if x>=8, it's not certain(the following will give the reason), so 1 is not sufficent
from 2 we can get that x is larger than 8, (x+24)/5=8, x=16, so if x is larger than 16 ,median is larger than average, if 8<x<16, median is smaller than average, 2 is not suffcient
and the two together are not suffcient
so E is right

明白了，多谢！

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