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数学PP请教2

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楼主
发表于 2006-7-11 16:50:00 | 只看该作者

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?

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沙发
发表于 2006-7-11 17:48:00 | 只看该作者
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
板凳
发表于 2006-7-12 03:42:00 | 只看该作者

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?

地板
 楼主| 发表于 2006-7-12 11:36:00 | 只看该作者
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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