本系列为同学们整理了GRE数学中出现的一些高频高质量的题目，并配有解析，希望同学们认真备考，都能取得好成绩

　　1.Each employee of a certain company is in either Department X or Department Y, and there are more than twice as many employees in Department X as in Department Y. The average (arithmetic mean) salary

is $25,000 for the employees in Department X and is $35,000 for the employees in Department Y.Which of the following amounts could be the average salary for all of the employees in the company?Indicate all such amounts.

　　A $26,000

　　B $28,000

　　C $29,000

　　D $30,000

　　E $31,000

　　F $32,000

　　G $34,000

　　本题我们要注意到题目中的more than twice的字眼，我们当做twice算的时候，结果是(25000*2+35000)/3约等于28333，因为有more than，所以选的答案要么是比前面这个数大，要么小，又由于more的是X部门的，那么肯定会将平均工资给拉低了，因此，选比前面那个数小的答案，AB都可以了。。

　　2.Working alone at its constant rate, machine A produces k car parts in 10 minutes. Working alone at its constant rate, machine B produces k car parts in 15 minutes. How many minutes does it take machines A and B, working simultaneously at their respective constant rates, to produce k car parts?　____________minutes

　　这类题目小学时候经常遇到，相信很多人都是这种感受哈

　　1/(1/10+1/15)=6min

　　1)If the dollar amount of sales at Store P was $800,000 for 2006, what was

　　the dollar amount of sales at that store for 2008 ?

　　A $727,200

　　B $792,000

　　C $800,000

　　D $880,000

　　E $968,000

　　直接算，800000*(1+10%)*(1-10%)=792000，即B

　　2)At Store T, the dollar amount of sales for 2007 was what percent of the

　　dollar amount of sales for 2008 ?

　　Give your answer to the nearest 0.1 percent.

　　___________%

　　直接算，1/(1-8%)=108.7%(约等于)

　　3)Which of the following statements must be true?

　　Indicate all such statements.

　　A For 2008 the dollar amount of sales at Store R was greater than that at

　　each of the other four stores.

　　B The dollar amount of sales at Store S for 2008 was 22 percent less

　　than that for 2006.

　　C The dollar amount of sales at Store R for 2008 was more than 17

　　percent greater than that for 2006.

　　本题A选项一看到就可以排除了，涉及到两个店的绝对量的比较，这个不确定，没有告诉绝对值。B选项是把两个增长的比例简单地算术相加。肯定错了。所以C肯定是对的了。。算一下也是的确是对的。。

　　3.A certain store sells two types of pens: one type for $2 per pen and the

　　other type for $3 per pen. If a customer can spend up to $25 to buy pens at

　　the store and there is no sales tax, what is the greatest number of pens the

　　customer can buy?

　　A 9

　　B 10

　　C 11

　　D 12

　　E 20

　　这个题首先就可以想到单价越便宜的我就能买的越多，因为它没有说两种笔一定要都买。

4.A list of numbers has a mean of 8 and a standard deviation of 2.5. If x is a

　　number in the list that is 2 standard deviations above the mean, what is the

　　value of x ?

　　x=_8+2.5*2=13_这道题不知怎么的，读题的时候度饶了，感觉很费解，什么是两个标准差，以为是个什么特殊的东西，后来问了同学才知道这就是个简单的计算题，没啥特别的，我的个汗啊，考试的时候我碰到了，我肯定错了。。

　　5.Frequency Distribution for List X

　　Number 1 2 3 5

　　Frequency 10 20 18 12

　　Frequency Distribution for List Y

　　Number 6 7 8 9

　　Frequency 24 17 10 9

　　List X and list Y each contain 60 numbers. Frequency distributions for each list are given above. The average (arithmetic mean) of the numbers in list X is 2.7, and the average of the numbers in list Y is 7.1. List Z contains 120 numbers: the 60 numbers in list X and the 60 numbers in list Y.

　　Quantity A Quantity B

　　The average of the 120numbers in list Z The median of the 120 numbers in list Z

　　A中，平均数肯定就是两组的平均数的和的一半，也就是(2.7+7.1)/2=4.9，因为两组的人数相同，而B中median就是(5+6)/2=5.5，所以就是B了。。

　　6.The figure above shows the graph of the function f in the xy-plane. What is

　　the value of f ( f (–1)) ?

　　A –2

　　B –1

　　C 0

　　D 1

　　E 2

　　这个题就是读图题了，一重重的往外算就好了，f (–1)=2，f(2)=1，即D

　　7.By weight, liquid A makes up 8 percent of solution R and 18 percent of solution S. If 3 grams of solution R are mixed with 7 grams of solution S, then liquid A accounts for what percent of the weight of the resulting solution?

　　A 10%

　　B 13%

　　C 15%

　　D 19%

　　E 26%

　　这个题小学也经常遇到，(3*8%+7+18%)/(7+3)=15%

　　8.Of the 700 members of a certain organization, 120 are lawyers. Two members of the organization will be selected at random. Which of the following is closest to the probability that neither of the members selected will be a lawyer?

　　A 0.5

　　B 0.6

　　C 0.7

　　D 0.8

　　E 0.9

　　这个就是组合的计算了， / =0.68(约等于)，所以选C吧，这个题可以用下那个计算器了。