GMAT数学中会涉及到一些统计学方面的概念知识，这也是考生在考试中经常遇到的一类题型，那么这些概念具体如何理解，今天小编就为大家统一介绍一下，希望对大家备考有所帮助。
1.平均数(average or arithmetic mean)
2.中数(median)
To calculate the median of n numbers，first order the numbers from least to greatest;if n is odd，the median is defined as the middle number，while if n is even，the median is defined as the average of the two middle numbers. For the data 6, 4, 7, 10, 4, the numbers, in order, are 4, 4, 6, 7, 10, and the median is 6, the middle number. For the numbers 4, 6, 6, 8, 9, 12, the median is (6+8 )/2 = 7. Note that the mean of these numbers is 7.5.
3.众数(mode)：一组数中的众数是指出现频率最高的数。
例：the mode of 7，9，6，7，2，1 is 7。
4.值域(range)：表明数的分布的量，其被定义为最大值减最小值的差。
例：the range of–1，7，27，27，36 is 36-(-1)= 37。
5.标准方差(standard deviation)：
One of the most common measures of dispersion is the standard deviation. Generally speaking, the greater the data are spread away from the mean, the greater the standard deviation. The standard deviation of n numbers can be calculated as follows:
(1)find the arithmetic mean ;
(2)find the differences between the mean and each of the n numbers ;
(3)square each of the differences ;
(4)find the average of the squared differences ;
(5)take the nonnegative square root of this average.
Notice that the standard deviation depends on every data value, although it depends most on values that are farthest from the mean. This is why a distribution with data grouped closely around the mean will have a smaller standard deviation than data spread far from the mean.
GMAT数学的基本概念，如果考生加以归类，会感觉没有想象中那么复杂和混乱。考生可以根据归类的GMAT数学基本概念，加以复习和记忆。还要提醒考生的是，GMAT数学的基本概念，最忌讳的是死记硬背，考生最好采用理解式记忆法，GMAT数学基本概念就能轻松搞定。
TIPS：GMAT数学易犯错误之疏忽大意
这是GMAT考试中最不应该犯的一类错误。基本上都是因为考试心态不端正，对数学存有轻慢态度才会出现的问题。解决方法也十分简单，那就是做完一遍复查一下。同时每次犯错都把错题汇总整理起来，定期拿出来回顾一下以避免再犯。因为疏忽大意而犯错是最容易复发的错误，因此反复回顾是非常必要的。
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GMAT数学整除题解题方法解析 http://gmat.zhan.com/tifen/31858.html
