2000以前至今的机警总结系列（一）

zhouxh

各位G友你们好，我八月考GMAT，现在我开始整理机警数学，从2000以前至今的有价值的机警题将陆续在阳阳的家中贴出，并且随题附上我的答案。对题目本身及答案有疑问的朋友请给予指点，希望与大家共勉。 （关注第9，12题，我不是很确定） 1,r方法和s方法（scale）不同，在r方法下的6，24分别对应s方法下的30，60，问要得到s方法下的100,应该在r方法下是多少?（答案中有60，84，我认为答案在72-96之间） 2，A要去出游，但她会在下雨的第一天日终回家，已知她是星期六开始旅行的，旅行头三天下雨的概率（each）分别是0.2，问张三在星期一回家的概率。 （0.8*0.8*0.2） 3，ax+by+c=0,slope是2/3，可以得到b吗？ （1） a=3 （2） c=-6 （A） 4，一个四边形是不是正方形？ （1） 角a+角b=180,两角相临 （2） 四边相等 （E） 5，2. A1=A2=1, Ak=Ak-1+2Ak-2,(note:k, k-1, and k-2 are at the lower right corners of A) where 3<=K<=16, what’s A7? (43) 6,There are 1200 respondants to a poll, each favoring their preference for candidates A, B, and C. 54% favored A, 48% favored B, and 42% favored C, and there is 30% favored both A and B. what’s the largest possible number of respondants favoring C, but not C & b , nor C & A?? (33) 7.A plane flied a distance of 800 miles at 360m/h with wind speed. And flied back at 260m/h with wind against it. What’s the average spped of the roundtrip? (约为302） 8，To travel trip of 40 miles… the speed for the first Y miles was X, and the speed for the remaining 40-y is 1.2X. what average speed? 1) x=12m/h 2) y=20 （C） 9，The “rule of 72”, defining the time needed for the investment to double, is K/2, where K means the percentage interest to be compounded yearly. If an investment of $10,000 is invested at the annual rate of 8%. And after the investment yields to be $20,000, and again be invested at the annual rate of 12%. Then according to the “rule of 72”, how long will it take the original to yield a total of $40,000?? （8/2+12/2=10） 10，4<(X-1)(X-1)<16，问X是整数的数目， 答案：2个。 11，一个人一年的income当中一部分花掉，另一部分存起来，利率是r。第二年存起来的部分每1dollar变成（1+r）dollar。第二年没有收入，将第一年存的钱用来花销，问如果第二年可供花销的的钱是第一年花掉的钱的1/2，那么第一年存的钱是收入的几分之几（1/2r+3 ） 12，k和p是positive constants，问以下那个方程一定有一个负数解。 I、 X*X+kX+p=0 II、 X*X-kX+p=0 III、 X*X+kX-p=0 选项：（A）I , (B) II, (C) III, (D) II and III (E) I and II and III （C） 13， every internal angle in a polygon is less than 180. how much is the average internal angle for a polygon: (1)there are two right internal angles (2)there are five vertices. （B） 14，there are two set A and B which only includes positive integer. A and B have the same number of positive integers. is the median of A greater than the average of B. (1) the items in A are even, the items in B is odd. (2) the sum of A is equal to sum of B. （E） 待续