41、GWD 6-37
42、A、B两个学生与其他3个学生坐成一排，问中间要么坐A要么坐B的排列数
SA: 没有很理解题意 我的做法是 P(4,4)*P(2,2)=48
43、长方形面积为4倍根3，宽为对角线的一半，问对角线长度
SA:4 对角线 宽 长构成 a 根3*a 2a
42.车行买一次算5,卖一次算3,最后车总数是14,求买卖共几次. [答案：6次.]
feifei七：39、一个出租车公司买入时(lots of five)一次买入5辆，租出时(lots of 3)一次租出3辆，如果买入5辆或租出3辆都算是一次，并且去年增长了14辆车，问一共是多少次。
A.3 B.4 C.5 D.6 E.7
流沙：设买入的次数是x，卖出的次数是y，则5x-3y=14。x= (14+3y)/5, 3y的个位数必须是6或者1，所以y=2，12，27等等。根据选项，y只能为2，x=4。选D
45、老JJ：退休占全部人员60%，其中20%参加了健康计划，健康计划的人占48%，问健康计划人里退休人员所占比例
SA:60%*20%/48%=25%
46、中号红衬衣所售数量是大号白衬衣的2倍，中号白衬衣是大号白的3倍，红卖了80，白卖了190，问共卖了多少中号的
SA: 应该是这样的题：见稿三80
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?
(费了我很多时间，因为我不确定那个as many... as到底是说哪个是哪个的多少倍，于是算了两种可能，最后选了个200，不知道对不对)
SA:200 suppose large red(lr)=x lw=y then mr=2y, mw=3x
x+2y=80 y+3x=190
47、老JJ：一个车每小时跑300MILE，问多少秒跑220FEET(有公式)
算比例的很多，数据充分性的题都不难。
http://forum.chasedream.com/dispbbs.asp?boardID=22&ID=131255&page=1
48. x,y,z,w, x is 20% 美国GREate than y, y is 20% 美国GREater than z, w is 20% less than x, how much percent 美国GREater of z is w?
SA: 15.2% (1.2*1.2*0.8-1)/1=15.2%
49. one company is planing to display some boxes, the first layer is one, the laster layer has 81 boxes,
and the every layer has one less row than the previous layer, and every layer has square shape,
ask the total number of boxes. I think the answer is 9^2+8^2+7^2+6^2+5^2+4^2+3^2+2^2+1
SA: a美国GREe
50. the problem about rent car, X company $15/day, $0.2/mile, the y company $20/day, $0.1/mile, asked if rent Xcompany’s car one day, it will need $25?
SA: 应该是这样的题吧
192.从 A公司租一车,每天fixed charged 15刀,每跑一mile 0.2刀,B公司租一车，每天fixed charged20刀,每跑一mile0.1 刀问从A公司租的凉车，跑了xmiles,charge和25刀比
1. B公司租一辆,跑了x miles,少于25刀
2. x<50 [答案D]
51.
The toll for crossing a certain bridge is $0.75 each crossing. Drivers who frequently use the bridge may instead
purchase a sticker each month for $13.00 and then pay only $0.30 each crossing during that month.
If a particular driver will cross the bridge twice on each of x days next month and will not cross the bridge on any other day,英语作文
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