本系列為同學們整理了GRE數學中出現的一些高頻高質量的題目，并配有解析，希望同學們認真備考，都能取得好成績

　　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

　　本題我們要注意到題目中的more than twice的字眼，我們當做twice算的時候，結果是(25000*2+35000)/3約等于28333，因為有more than，所以選的答案要么是比前面這個數大，要么小，又由于more的是X部門的，那么肯定會將平均工資給拉低了，因此，選比前面那個數小的答案，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

　　這類題目小學時候經常遇到，相信很多人都是這種感受哈

　　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%(約等于)

　　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.

　　本題A選項一看到就可以排除了，涉及到兩個店的絕對量的比較，這個不確定，沒有告訴絕對值。B選項是把兩個增長的比例簡單地算術相加。肯定錯了。所以C肯定是對的了。。算一下也是的確是對的。。

　　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

　　這個題首先就可以想到單價越便宜的我就能買的越多，因為它沒有說兩種筆一定要都買。

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_這道題不知怎么的，讀題的時候度饒了，感覺很費解，什么是兩個標準差，以為是個什么特殊的東西，后來問了同學才知道這就是個簡單的計算題，沒啥特別的，我的個汗啊，考試的時候我碰到了，我肯定錯了。。

　　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，平均數肯定就是兩組的平均數的和的一半，也就是(2.7+7.1)/2=4.9，因為兩組的人數相同，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

　　這個題就是讀圖題了，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%

　　這個題小學也經常遇到，(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

　　這個就是組合的計算了， / =0.68(約等于)，所以選C吧，這個題可以用下那個計算器了。