易出错GRE数学难题详细解析

>>GRE考试试题：易出错GRE数学难题详细解析

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1.Each employee of a certain company is ineither Department X or Department Y, and there aremore than twice as many employees in Department Xas 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 ofthe following amounts could be the average salaryfor all of the employees in the company?Indicate allsuch 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 manyminutes does it take machines A and B, working simultaneously at their respective constantrates, 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 givenabove. The average (arithmetic mean) of the numbers in list X is 2.7, and the average of thenumbers in list Y is 7.1. List Z contains 120 numbers: the 60 numbers in list X and the 60numbers 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。

相信上面的内容一定可以帮助大家更有效率的备考，从小学开始，数学都是一个需要题量练习的科目。在大家备考中，出来夯实基础之外，练习真的很重要。想要提高自己的GRE考试成绩，就来坦途网GRE考试频道看看吧，这里有关于考试的技巧详细介绍。