GMAT数学的相关问题和大家做一个解读，希望对大家备考起到一定的帮助。
描述统计(descriptive statistics)
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 ;
本文就是小编为大家总结的关于GMAT数学概念的解读，希望对大家有所帮助!
(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。最后祝愿大家都能取得一个不错的成绩。