急:提问几道GRE数学题1.A/x + A/y=1.In this formula,x and yrepresent the time needed for each of two workers to complete the job alone; Arepresents the time it takes for both x and y to complete the job workingtogether.So each fraction represen

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急:提问几道GRE数学题1.A/x + A/y=1.In this formula,x and yrepresent the time needed for each of two workers to complete the job alone; Arepresents the time it takes for both x and y to complete the job workingtogether.So each fraction represen
急:提问几道GRE数学题
1.A/x + A/y=1.In this formula,x and y
represent the time needed for each of two workers to complete the job alone; A
represents the time it takes for both x and y to complete the job working
together.So each fraction represents the portion of the job completed by a
worker.
请解释该公式含义,没太看懂,尤其没明白A/x是什么意思
2.牛吃草问题：牧场上有一片匀速生长的草地,可供27头牛吃6周,或供23头牛吃9周,那么它可以供21头牛吃几周?（P86）
3.鸽巢原理：有0-9这十个数字分别写在10张卡片上,随机从这10张纸片中抓,问至少抓几个纸片才能保证所抓纸片上必有两个纸片上所写数字相加等于10?（P88）
彻底晕菜,
4.Fred is twice as old as Geri was 4 years
ago.Holly is five years older than Geri will be one year from now.
答案是F=2(G-4),H=G+6.为何不是F-4=2(G-4),H+1=G+6?

急:提问几道GRE数学题1.A/x + A/y=1.In this formula,x and yrepresent the time needed for each of two workers to complete the job alone; Arepresents the time it takes for both x and y to complete the job workingtogether.So each fraction represen
1、比如一件事甲单独干需要2小时（x=2）,乙单独干需要3小时（y=3）,甲乙一起干需要多少时间呢?这个你会算吧?等于“五分之六”小时（A=6/5）.然后你按照公式列出来算一下,就会发现两边是相等的.【A的算法是用1除以（1/2+1/3）】
2、设每头牛每周吃的草为1,这片草地原有的草数为x,草地每周长出的草为y,则
x+6y=27*6
x+9y=23*9
解得x=72,y=15（这片草地原有草72,每周新长出15）
设21头牛吃掉全部的草需要n周,则
21n=72+15n
解得n=12
所以这片草地可以供21头牛吃12周.
3、我不大会概率.我觉得是7张,因为比较极端的情况就是你抓的数都在0-9的一端（比如都是最小的）,但即使是这样,抓到6张的时候（012345）后面不管抓到什么也都能和前面的某一个数凑成10了.不知道对不对.
4、你没明白答案是因为没看懂句子.句子的意思是：F的岁数是G四年前的岁数的2倍.H比G一年后的岁数大5岁.所以答案写的是没错的.
【花了一早晨才想明白所有的问题,尤其是第2道.不清楚欢迎追问.】

第二题吃十二周

楼主去尚友GRE备考去搜一下吧，那里有很多GRE的考友们分享问题，解决问题，希望对你有帮助~~

就是说FRED现在（用的is）的年龄是GERI四年前年龄的2倍，不是说FRED4年前的年龄（否则要用was)是GERI四年前年龄的2倍

几道GRE数学题急:提问几道GRE数学题1.A/x + A/y=1.In this formula,x and yrepresent the time needed for each of two workers to complete the job alone; Arepresents the time it takes for both x and y to complete the job workingtogether.So each fraction represen 几道简单的GRE数学题1 two successive discounts of 20 percent and 40 percent are equivalent to a single discount of x percent. x 522 the number of ¼-inch lengths in a 4-inch length 一.括号部分提问.二.还有几道数学题不知道怎么列比例式方程1.I （take the bus 提问）to school.2.he bought (a book 提问) last week.3.she (watched tv 提问) yesterday.1.1/2X：3/8=1.22.3/8：X=1/3:1/103.10.5/X=0.5*0.7/4 几道GRE数学题1.In a series of races,10 toys cars are raced,2 cars at a time.If each car must race each of the other cars exactly twice,how many races must be held?2.The daily rate for a hotel room that sleeps 4 people is $39 for one person and x 提问几道GRE绿皮数学题P58The toll for a certain bridge is $0.15 or 1 token.Tokens are sold in packs of 40 for $4.00.The percenty save on 40 trips across the bridge if a token,rather than $0.15,is used to pay each toll与66又2/3比大小答提问几道GRE数学题P48A number between 5 and 10与A number between 8 and 14比大小答案是不确定The number of different positive divisors of 12与the number of different positive divisors of 50比大小 P49x,y,z are positive integers,and 提问几道GRE数学题!都是绿皮上的,本人数学不大好,P275.39In how many of the integers between 1 and 100 does the digit 5 occur exactly once?答案是18,题目啥意思,如何做?P231.2A train travels 60 miles per hour for 3 hours and t 嗯、几道数学题哈.1.如果关于x的不等式（a-1)x 高一集合的几道数学题..请一定要帮忙..1.设A={x|-4 急!几道高中数学题,详细解释急,几道简单的离散数学题, 求学霸,几道小学数学题,急提问几道GRE数学!急!都是绿皮上的,本人数学不大好,请尽可能详细解释,谢谢!180.36If 2/3 of the number of women attending acertain dance is equal to 1/2 the number of men attending, what fraction ofthose attending are women?A.2 提问几道GRE数学题1.若自然数n被3除余2,被4除余1,问n被12除余几?52.2001年的元旦是星期六,问2002年的元旦是星期几?周日用到同余理论?3．若自然数n是完全平方数,则根号下n也为n的一个因子,在n 初高中衔接的几道数学题1.已知函数f(x)=ax²+4x+bx(a 提问几道数学题.**** 要有答题过程、思路.答案我知道.1.方程组 3次√（x＋1）＋3次√（y-1）＝2 的解是（）.x＋y＝262.若对任何实数x不等式ax>b都成立,那么a、b的取值范围是____________.还有一几道有关集合的数学题. 谢谢一.求集合A,B的交集.1. A={X l 0