2005年09月数学机经讨论稿第三篇(66--100)
分类: GRE-GMAT英语
3。 66. x(x-5)(x+3)=0,x? (1) x^2-2x-15非0 (2) x^2-7x非0 [c] SA:大家注意下这一题 如果是c 那怎么解释呢 x不是无解了?? 我想是不是问唯一解 选A 67. x非零整数 x(x+4)(x+5)能被几除? I. 3 II.忘了 III.6 答案I III SA: agree 68. 以两点(-1,3)(2,-1)为以正方形的对角线,问周长 答案 好像10根号2 SA:agree 69. x^2-6xy+9y^2=16, (x-3y)^4=? 答案 256 70. [x]表示不小于X的最小整数(跟一般定义不同,注意了),[2x]是否0? (1) [x]=0 (2)[3x]=0 答案 B SA: B 71. 一个人为子女存钱,每月会比上个月多存一定数目的钱,一开始存800(不是第一个月),第7个月存的钱是第3个月的两倍,问每个月比上个月多存多少? 答案 800 SA:800 ...800+7X=2(800+3X) 这题有争议,这个答案是jj作者给的答案,jj作者考了数学满分,所以就按他的答案做了,大家上场看清楚题目,应该差不多。 72. 一个盒子3*3inch的底,11inch的高,问upright放到一个3*9feet,1foot高的盒子中,最多放多少个?(一开始我不明白upright放到底算怎么放,后来算了两种可能都一样) 答案好像是432 SA: 432 There are twelve inches in a foot. 3*9suqre feet=3*9*12*12 square inchs upright指正着放把 底在下面 n=3*9*12*12/3*3=432 73. A机器干某事,10,000的量用了8小时,和B一起干用了6小时,问B单独干每小时干多少? 答案好像是416.7 SA: agree Hb=10000/6--10000/8= 416.7 74. 一个人6年前存钱,算复利,问本金和现在比的ratio (1)如果以12%算,3年的时候有多少(具体数字) (2)本金是多少(具体数字) 答案A SA: agree principal * 1.12^3=XXX xxx/principal 可求 75. the average of 4,8,y is less than or equal to 80, what is the greatest possible value of y? (228)(这是第一题) SA: 80*3-4-8=228 76. 等边三角形内切圆面积9v3,圆面积?(12pai) SA:SA:12派 三角形边长6 园半径2根号3 题目貌似有问题 见稿一11道 估计应该是外接圆 77. 10 种邮票,Gorge 有三种,从这10种里选2种,the probability that Gorge has neither of them. (7/15) SA: agree 7/10*6/9=7/15 78. A, B and 3 kids are seated in front of the class, how many 排法 if A or B are seated right in the middle? (2P(4.4)) SA: agree, 稿二42 79. .鹅蛋问题,隐约记得以前机经里有。一共6804个蛋,是这么得来的,get 2 eggs from 90 percent of the nests which have5 or more eggs, and no egg from other nests. 知道有320个nests which have 4 or less eggs. 问一共多少nests?(不记得答案了) SA:6804/2/0.9+320=3780 80. 一个店 sell medium and large 红衬衫还有medium and large白衬衫. It sold twice as many medium red shirts as large white shirts and 3 times as many medium white shirts as large red shirts. It sold 190 white shirts and 80 red shirts, how many medium shirts did it sell? SA:200 suppose large red(lr)=x lw=y then mr=2y, mw=3x x+2y=80 y+3x=80 ---> x=60 y=10 ---> 2x+3y=200 81. 1/(vn+1-vn)=? SA: -1/(vn+1)(vn) v表示根号 82. 13679*((10^6-10^4)/10^5)) 的百位数?(2)(最后一题) SA: 4 原式=13679*(10-1/10) 百位数136790-1367.9 83. speed at 72 kilometers per hour. what is the speed in terms of merters per second? (20) SA: 72*1000/60*60=20 84. buy one get one half if the second one is less or equal value. The customer buy a second pair of shoes with 65 percent price of the first pair? In total, what percent discount did she get? (20%)算出来时(19.6%) SA: (65%/2)/(1+65%)=0.1969696 D.S. 85. What is n? (1) the remainder of n devided by 3 is 2 (2) the remainder of n^2 divided by 3 is 1. SA:E 我是试出来的n=3a+2 n^2=3b+1 n=5,8已经都可以了 有没有别的解法 86. 给了摄氏和华氏的换算公式,is low temperature less than 30F? (1)low temperature is greater than negative 5c (2) low termperature is less than negative 2c SA: B 87. 40 miles per hour from A to B and 45 miles/hour from B to A. the distance from A to B? (1) total time 34 minutes (2) take 2 minutes less from B to A than from A to B (D) SA: D (1) S/40+s/45=34/60 (2)s/40-s/45=2/60 88.给了温度计的图,上面由X,Y,Z刻度,能不能求出X?不记得条件了,好像以前机经上有。不难就是了 SA: D 可能是稿一40 89. 最让我心痛得终于出场了。 if x+y=z? (1) absolute value of X=Y-Z (2)X12,则带进去试一下,4+C42=10不满足,5+C52=15满足,所以答案是5种颜色 参考GWD-9-2...题目意思完全一样 98. xy^2z^3>0,问x>0吗? (1) xy>0 ; (2) x>y SA: E 99. 2^100+3^101+4^102的个位数是多少 就是求除以十的余数,各位兄弟姐妹们不了解同余概念的可以背答案,答案是5,放心不会错的 100. 有图,图型是一个三角形三个角的补角,分别是x, y,z,问x=? (1) x=y; (2)y=z; 答案c