在
在参加GMAT考试前，大家都会细心备考GMAT数学词汇，除此之外，GMAT数学备考之描述统计，包括：平均数、中数、众数、值域以及标准方差。
GMAT数学备考之描述统计(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
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.
以上是小编总结的GMAT考试解题策略之数学统计。
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