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GRE數學培訓_GRE數學真題解析(精選一)
時間:2020-07-09
來源:朗思教育
作者:Eric chen
1.
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.
【解析】A
質數是指只能夠被1和它本身整除的正整數
A:大于24最小的質數就是29
B:小于28最大的質數就是23
2. From 2011 to 2012, Jack`s annual salary increased by 10 percent and Arnie`s annual salary decreased by 5 percent. If their annual salaries were equal in 2012, then Arnie`s annual salary in 2011 was what percent greater than Jack`s annual salary in 2011 ?
Give your answer to the nearest 0.1 percent. _____%
【解析】15.8
設2011年Jack和Arnie的年收入分別是x和y
那么2012年Jack和Arnie的年收入分別就是x*(1+10%)=1.1x和y*(1-5%)=0.95y
2012年兩人的年收入相等,所以1.1x=0.95y,可以解得y≈1.158x,即y比x高出15.8%
3. In 1993 a card company that sold 40 percent of the Mother`s Day cards that year priced its cards for that occasion between $1.00 and $8.00 each. If the revenue from sales of the company`s Mother`s Day cards in 1993 was r million dollars, which of the following indicates all possible values of r ?
A 155 < r < 1,240
B 93 < r < 496
C 93 < r < 326
D 62 < r < 744
E 62 < r < 496

【解析】E
1993年該公司銷售了當年40%的母親節賀卡,每張賀卡的價格在1美元到8美元之間,根據右邊的圖形可知,1993年母親節賀卡總量是155million,其40%的就是155*40%=62million
那么這部分的銷售總收入介于62million和62*8=496million之間。
4. A group of 5,000 investors responded to a survey asking whether they owned stocks and whether they owned bonds. Of the group, 20 percent responded that they owned only one of the two types of investments. If r is the number of investors in the group who owned stocks but not bonds, which of the following represents the number of investors in the group who owned bonds but not stocks, in terms of r ?
A 5,000
B 1,000 – r
C r – 1,000
D 1,000r
E (0.2)*(5,000 – r)
【解析】B
設持有股票的是A集合,持有債券的是B集合
根據題意可得只屬于其中一個集合的是A+B-2*A∩B=5000*20%=1000;
只屬于A集合的是r,r=A-A∩B;
需要求的是只屬于B集合的,也就是B-A∩B=1000-r.
5. The 5 letters in the list G, H, I, J, K are to be rearranged so that G is the 3rd letter in the list and H is not next to G. How many such rearrangements are
A 60
B 36
C 24
D 12
E 6
【解析】D
指定位置型排列,優先排特殊的元素
G在第三位,只有一種方法;H不能和G相鄰,那么H的排法有C(2,1)種;最后排剩下的三個字母的排列有A(3,3)種;
所以一共有C(2,1)*A(3,3)=12種排列方法。
6. From the 5 points A, B, C, D, and E on the number line above, 3 different points are to be randomly selected. What is the probability that the coordinates of the 3 points selected will all be positive?
A 1/10
B 1/5
C 3/10
D 2/5
E 3/5

【解析】A
從坐標軸可以看出是負數的有兩個點A和B,是正數的有三個點C,D,E
如果要求選出來的三個點都是正數的話,只能是組合{C,D,E},只有1種;
而從該五個點當中隨機選出三個點的組合數有C(5,3)種;
所以選到三個點都是正數的概率就是P=1/C(5,3)=1/10.
7. In the xy-plane, a quadrilateral has vertices at (-1, 4), (7, 4), (7,-5), and (-1, -5). What is the perimeter of the quadrilateral?
A 17
B 18
C 19
D 32
E 34
【解析】E
設這四個點分別就是A(-1, 4), B(7, 4), C(7,-5), and D(-1, -5)
那么AB=CD=8, BC=DA=9
四邊形ABCD的周長就是2*(8+9)=34.
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