首页 >> GRE/GMAT学习经验>>正文
GRE数学想考满分？这6大失分点要关注
时间：2020-08-11
来源：网络
作者：admin
相较于Verbal，GRE的Quantitative部分是绝大多数同学的得分利器，大家的目标也基本都锁定在168+，甚至于满分。虽然GRE数学考察的内容相对来说比较容易，但想要考一个满分也并不如想象中的那么轻而易举。尤其近年来，难题、坑题出现的频率逐渐变高，考生在考场上一不小心就会失分。
一、没有仔细读题
例题
Of the students in a school, 20 percent are in the science club and 30 percent are in the band. If 25 percent of the students in the school are in the band but are not in the science club, what percent of the students who are in the science club are not in the band?
A. 5% B. 20% C. 25% D. 60% E. 75%
比如上面这题,问的是在science club的学生中不在band里面的百分比, 所以得用15%/20%=75%, 而不是直接等于15%.
二、几何题中主观做出题目没给出的假设
例题：∠C=89°.
Quantity A: Length of AB
Quantity B: Length of BC
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.
答案是D，因为在GRE数学考试中并不保证图形会按照相应的比例绘制：there’s no guarantee that a figure will be drawn to scale on the GRE.
三、忘记 0 和 1
例题：If x is an odd negative integer and y is an even integer, which of the following statements must be true?
I. (3x - 2y) is odd
II. xy2 is an even negative integer
III. (y2-x) is an odd negative integer
A. I only
B. II only
C. I and II
D. I and III
E. II and III
答案: A. 容易错选C, 如果y是0, xy^2就不是negative integer.
四、忘记最小的质数
例题
n is an even integer.
Quantity A: The number of prime factors of n
Quantity B: The number of prime factors of n/2
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. 最小的质数是2,也是唯一的偶数。当n=2 的时候, Quantity A 是一个prime factor, Quantity B是0个prime factor当n=4的时候, Quantity A和Quantity B相等
五、没有区分“must be” and “could be”
例题
c and d are prime numbers. If c – d is an odd integer, then which of the following must be true?
A) c is even
B) d is odd
C) c*d is odd
D) d is even
E) c*d +1 is odd
因为c和d都是prime且要满足c-d是odd, 说明c和d一个是odd, 一个是even. 在所有prime中只有2是even, 所以c和d中一定有一个是2. 选项中 A,B,D都是could be true, C选项 c*d 一定是even. 所以答案选E.
Must be = Always correct
Could be = answer only holds true in certain instances
六、没有注意符号单位
例题
Quantity A: 0.05 percent of 4000
Quantity B: 1/200 of 4000
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.
计算的时候 percent 需要除以100, 所以0.05 percent of 4000= 0.05*4000/100 = 2, 所以答案选B。
遇到以上六种情况，同学们一定要保持警惕、多多思考。找出陷阱，直击正确选项！
一、没有仔细读题
例题
Of the students in a school, 20 percent are in the science club and 30 percent are in the band. If 25 percent of the students in the school are in the band but are not in the science club, what percent of the students who are in the science club are not in the band?
A. 5% B. 20% C. 25% D. 60% E. 75%
比如上面这题,问的是在science club的学生中不在band里面的百分比, 所以得用15%/20%=75%, 而不是直接等于15%.
二、几何题中主观做出题目没给出的假设
例题：∠C=89°.
Quantity B: Length of BC
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.
答案是D，因为在GRE数学考试中并不保证图形会按照相应的比例绘制：there’s no guarantee that a figure will be drawn to scale on the GRE.
三、忘记 0 和 1
例题：If x is an odd negative integer and y is an even integer, which of the following statements must be true?
I. (3x - 2y) is odd
II. xy2 is an even negative integer
III. (y2-x) is an odd negative integer
A. I only
B. II only
C. I and II
D. I and III
E. II and III
答案: A. 容易错选C, 如果y是0, xy^2就不是negative integer.
四、忘记最小的质数
例题
n is an even integer.
Quantity A: The number of prime factors of n
Quantity B: The number of prime factors of n/2
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. 最小的质数是2,也是唯一的偶数。当n=2 的时候, Quantity A 是一个prime factor, Quantity B是0个prime factor当n=4的时候, Quantity A和Quantity B相等
五、没有区分“must be” and “could be”
例题
c and d are prime numbers. If c – d is an odd integer, then which of the following must be true?
A) c is even
B) d is odd
C) c*d is odd
D) d is even
E) c*d +1 is odd
因为c和d都是prime且要满足c-d是odd, 说明c和d一个是odd, 一个是even. 在所有prime中只有2是even, 所以c和d中一定有一个是2. 选项中 A,B,D都是could be true, C选项 c*d 一定是even. 所以答案选E.
Must be = Always correct
Could be = answer only holds true in certain instances
六、没有注意符号单位
例题
Quantity A: 0.05 percent of 4000
Quantity B: 1/200 of 4000
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.
计算的时候 percent 需要除以100, 所以0.05 percent of 4000= 0.05*4000/100 = 2, 所以答案选B。
遇到以上六种情况，同学们一定要保持警惕、多多思考。找出陷阱，直击正确选项！
