GRE数学词汇,概念,实例(4)

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编辑点评: GRE数学增加了难度,不过,小编相信,我们中国的考生还是hold住的~~在这种情况下,了解数学词汇,端正数学基本概念和熟悉相应实例非常重要。来看下面这个系列吧。

GRE数学增加了难度,不过,小编相信,我们中国的考生还是hold住的~~在这种情况下,了解数学词汇,端正数学基本概念和熟悉相应实例非常重要。来看下面这个系列吧。

一元二次方程

ax2+bx+c=o

x12=[-b±(b2-4ac1/2)]/2a

描述统计 Descriptive statistics

mode 众数

一组数中出现频率最高的

极差 range

一组数中最大值与最小值之间的差值

平均数 mean

算术平均 arithmetic mean

几何平均 geometric mean

例题.The circumference of a rectangle is 20

A.The greatest area of the rectangle

B.25

中位数 median

中位数的寻找方法:

1.将所有n个数字按着从大到小或者从小到大排列;

2.如果n=奇,整个序列中位于中间位置的数就是中位数;如果n=偶,中间两个数的算术平均即是中位数。

例题.If the arithmetic mean of a, b, c, 3 and 5 is 6, which of the following must be true?

1.The median of the five numbers cannot be 3

2.At least one of a, b and c is greater than 7

3.The range of the five numbers is 2 or more

A.1 only

B.2 only

C.3 only

D.1 and 3

E.2 and 3

例题.A group of students were tested on data-entry skills, and the number of errors they made and the percent of students making x errors were recorded as follows.

Number of errors

Percent of students

0

1%

1

7%

2

8%

3

25%

4

19%

5

18%

6 or more

22%

1. What is the range for the number of errors made by the students in the sample?

A. 4

B.5

C.6

D.7

E. It cannot be determined from the information given.

2. What was the median number of errors in the sample?

A.3

B.3.5

C.4

D.4.5

E. It cannot be determined from the information given.

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