一道数学题

单选题。
10个数，Median 70, average 70.5, range 12,再加一个74， 以下什么会变？
1. average only
2. Median
3. Range only
4. average and mean
5. range and mean

除了穷举法有什么好办法解么？

错了，是4. average and median 5. range and median

这个题应该是说一定会变的是什么，因为上述几个参数都可能变。
一定会变的就是Mean咯，因为新加入的数74不等于原来的平均值70.5。然后就是Average跟mean的区别，我查了一下，大概是说Average是最能代表一组数的值，mean只是其中一个，所以Average也会变化。

Summary:

1. Average can be in mean (arithmetic mean), median, or mode. Mean is basically a form of describing an average of the sample.

2. Mean can be in many various types too, but only the arithmetic mean is considered as a form of average.

3. ‘Average’ is usually used in casual English conversation, while ‘mean’ is usually used in technical language.

Read more: Difference Between Average and Mean | Difference Between | Average vs Mean http://www.differencebetween.net/science/difference-between-average-and-mean/#ixzz3DS6mPzr9

redsilence 发表于 2014-9-16 13:07
错了，是4. average and median 5. range and median

那就是选1吧

我是直接分析：
1.只要加的数不是70.5，平均数肯定变了。
2.原中位数是 排序后第五和第六个数的平均70，说明第五个比70小，第六个比70大，或者两个都是70.加入74肯定比第五位大，中位数向右移动到第六位数，如果原来第六位是70，那就不变，否则就变了。
3.range要变的话，肯定74比以前的最大值还大了，这个从题目看不出来把。

确切的说average一定会变，其他未必，所以1

谢谢谢谢谢谢