2017年8月25日GRE数学机经预测

题目

1. The roots of the equation x^2 - x - 6 = 0 are

A, 1 and - 5

B. 2 and - 3

C. 3 and - 2

D. 5 and - 1

E. none of the above

答案：C

解析：方程式可转变为(x-3)(x+2)=0, roots也就是方式的根即为3和-2。

2. Quantity A：The least prime number greater than 24

Quantity B：The greatest prime number less than 28

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.

答案：A

解析：大于24的最小质数为29，而B的任何一个数字都小于28，因此选A。

3. Quantity A：54% of 360

Quantity B：150

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.

答案：A

解析：无需具体计算A，大致计算360的50%为180大于B即可。

4.

Quantity A：PS

Quantity B：SR

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.

答案：D

解析：根据条件可知三角形为等腰三角形，但缺乏其它条件因此无法判断PS和SR的长度，无从比较，所以选D。

5. A merchant made a profit of $5 on the sale of a sweater that cost the merchant $15. What is the profit expressed as a percent of the merchant’s cost? Give your answer to the nearest whole percent.

答案：33%

解析：卖了件cost15块的衣服，赚到了5元profit，求profit和cost的百分比，也就是5/15，因为要求整数，因此约等于33%