2017年9月23日GRE考试数学机经预测

　　题目

1. Points R, S, and T lie on a number line, where S is between R and T. The distance between R and S is 6, and the distance between R and T is 15.

Quantity A：the distance between the midpoints of lines segments RS and ST

Quantity B：the distance between S and T

A. Quantity A is greater.

B. Quantity B is greater.

C. The two quantities are equal.

D. The relationship cannot be determined from the information given.

　　正确答案：B

题目解析：Quantity A长度为RT的一半，7.5，Quantity B长度为15-6=9，因此选B。

2. x, y, and z are the lengths of the sides of a triangle.

Quantity A：x y z

Quantity B：2*z

A. Quantity A is greater.

B. Quantity B is greater.

C. The two quantities are equal.

D. The relationship cannot be determined from the information given.

正确答案：A

题目解析：两边之和大于第三边，x y>z. 所以x y z>2*z

3. Rectangle R has length 30 and width 10, and square S has length 5. The perimeter of S is what fraction of the perimeter of R ? ___/___

　　正确答案：20,80

题目解析：R周长为80，S周长为20，按照题目要求，前面填入20，后面填入80。根据OG解释，考生如果约分为1/4也是正确的。

4. 1, –3, 4, 1, –3, 4, 1, –3, 4,..

In the sequence above, the first 3 terms repeat without end. What is the sum of the terms of the sequence from the 150th term to the 154th term?

正确答案：7

题目解析：题目说前三项无限循环， 所以1，-3， 4 是一个循环。150th正好是4，然后以此类推，150th到154th的和 为4 1 (-3) 4 1=7

For which of the following bird species is the standard deviation of the numbers of sightings shown for the four seasons least

A. Cardinal

B. Junco

C. Robin

D. Sparrow

E. Wren

　　正确答案：D

题目解析：此题解题要点有两个，首先考生需要理解standard deviation也就是标准差的概念。其次标准差计算公式较为复杂，强行计算会花费大量时间，因此需要省时解法，大家可以观察各组数据找出四个数据差异最小的一组，即为正确答案，因此选D。