[原创]11月数学机经221-255题讨论稿

ruthere

221) abc不等于零。a^2b^5c^(-4)>0?
      1.a^2b^5>0
      2.b^5c^(-4)>0   
答案: D
思路:

222) 是否 xy    (1). xyz=1;
    (2). xyz^2>1
答案: C
思路: old jj

223) 说一个邮递服务项目收基本费 3 元， 然后每个发运的东西价格是19。95 员。问总共发了多少个东西？
  （1）。 发运的东西总价值介于 200 与 225 元之间；
  （2）。 发运的东西总价值介于 185 与 205 元之间；
         （ the figures above are not necessarily correct, but the logic is the same）
答案: E
思路:

224) 一个数 A=xwyz, x, w, y, z 全部为质数， 问除了1 和 A 之外 其它是 A 因子
的个数？
   （1）。 8
   （2）。10
   （3）。 11
   （4）。12
   （5）。 14
答案: E
思路:

225) 说三个整数的和是40， 其中最大数是中间那个树的3倍，而最小的数比最大的那个数小23，问这三个数的乘积是多少？
答案: 972
思路: 4*9*27

226) 老jj, 说有7个记者，想选2个人组成一个记者团，有多少个选法？
答案: 21
思路: C72

227) 说一个圆里套了一个正方形，告诉圆的周长，让求正方形的周长。
答案: 不全
思路:

228) 说一个圆的半径是2，其中有一个120度的扇形， 该扇形的玄与其两个半径组成一个三角形，求这个三角形的面积。
答案: 根号3
思路:

229) 白痴题，一个数 A=wyz, w, y, z 全部为质数， 问A 的 因子的个数？
答案: 8
思路:

230)  7^85+4的个位数(答案1)
答案: 1
思路:


231) 某人卖两种东西，A和B，其中A的PROFIT是其价格的10％，B的PROFIT是其价格的90％，A的COST是B的COST的3倍，问一个A和一个B，其总的PROFIT是其总的价格的百分之多少？（解的时候注意价格里包括PROFIT就可以了。）
答案: （解的时候注意价格里包括PROFIT就可以了。）
思路:


232)（图形）从一点出来二条射线，夹角是65度（数字可能不对），一个三角形的二点分别在射线上，另一点在射线的边界之内，而且是在放射的方向（也就是在前面说的三条线组成的三角的外侧）。这个顶点所在的角是Y，另外的两个角（三角形）分别是K和M，而且K外面的角也是K，M外面的角也是M。求Y。（大家结合我的求解来理解这题吧！
gemj答案&思路:  (180－2K)＋（180－2M）＋65＝180（算出K＋M的值，代入下式）
             Y＝180－（K＋M）

233）有一个镇里的人都有汽车，有2辆占了5/8，一辆的有63人，问总的汽车数。我差点弄成总人数去了，大家也要小心。
答案: 273
思路:

234)DS:有一堆东东，在180-220之间（好像）分成8堆还余4个，问一共有多少个
a分成9堆一个不剩
b分成12堆一个不剩。
这道题花了我5分钟好像108满足这两个条件，应该选c,我太紧张了，居然按错了！
答案: C
思路:

235)Mprtz>0,which of the following must be positive?
I mp>0
II rt>0
III tz>0
---------- the last question
答案: I & II
思路:

236)eat pie?? Tracy ate 1/2, the other ate the 1/4 of the remaining, ask what faction of the pie is left?
答案: 3/8
思路:

237) one very strange: DS:
can determine x*x+y*y ?
1) 2x + 3y= 6
2) x/3+ y/2=1
-----------two conditions are the same, sure, I double checked them E
答案: E
思路:

238) simple annual interest:
one investment ‘s interest rate is x, other investiment is $5000(not sure ), interest rate is y
ask what is the first investment ? making the interest on these two investment to be same at the end of the year.
1) the interest at the end of the year is$….(a number)
2) y=2x  (or x=2y)
答案: B
思路:

239)one buy n things at a total cost of t, and sell out they at the price for pre stuff is $d, if he will buy
and sell 100 this kind of thing at $d, ask the profit he will get?
答案: 100d – 100t/n
思路:

240)1, 11,111,…. Ask what is the tenth digit of the sum of first 40 number in this sequences?
答案: 3
思路: http://forum.chasedream.com/dispbbs.asp?boardID=22&ID=25696

241) sequence I: a1, a2,….. a10
sequence  II: r1,r2,……r10
ri is the remain of the ai divided by 2, what is the sum of sequence II
1) there are six numbers in sequence II
2) the sum of sequence I
答案: A
思路: old jj. 1) there are six numbers in sequence II = even

242)a teacher teached 3 classes A,B,C, the average score is 65,80,77. the ratio of number in the class A,B,C is 4: 6:5, ask the average…(not sure if the particular number is right, I get 75)
答案: 不全
思路:

243)xy+z=1
xyz=3/16
x+y=1
ask what is the value of squarte root of 1/x+1/y+1/z-3/16
(逐个通分，代入条件)
答案: (247/48)^1/2
思路: (逐个通分，代入条件)

244)a word is made of 3 characters: the second is made of one of vowel number (a,e,I,o,u); the first and third are different, and made of unvowel numbers
ask what is the total possible number?(2100)
答案: 2100
思路: old jj

245)x=5^y, x=(1/5)*x*y^2
ask what is 625
答案: 不全
思路:

246)1 red stuff, 3 green stuffs, choose 2 of them randomly, ask what is the probrability of choose both of 2 are green?
答案: 1/2
思路: C32/C42

247)one get salary in the following way: 500 + (x thousand – 5000)*10%, ask the express of the salary in terms of x
答案: 不全
思路:

248)xy=1,
x=2^(-5)*5^3
ask what is y?
答案: 2^5 * 5^-3
思路:

249)cotton and soybean:
total sales of them are …; price of cotton is 80; cost of soybean is 40
ask what is amount of cotton?
1) the total amount of cotton and soybean is …
2) the ratio of them are…(not sure)
------anyway, the answer is D
答案: D
思路: old jj#156

250)In a circle, the radium is 2, the angle of the triangle is 120 degree, ask what is the area of the triangle in this circle
------squarte root of 3
答案: 3^1/2
思路: old jj#228

251)one 四边型, one angle is 50 degree, others are expressed as k,x,y
ask what is y?
------- can not describe it in detials, but you can figure out it when you see it. The answer is 65 degree
答案: 不全
思路:

252)the area or rectangle is 80
what is the perimeter?
1) the long one is 2 more than the short one
2) the length of the longer one is 10
答案: A
思路:

253)In a order, the shipment fee is $3, the price is $19.95
ask the exact number of the things in the order?
1) total cose is between 210 and 225
2) total cost is between 190 and 215
-------I get B, not sure whether I remember the right numberof the range of the total cost
答案: C
思路:

254)the most difficult question in my test:
survery of 800 students to two things’s attitude---- M and R
the response can be YES, NO, Not sure
the table in the question tells us that:
to M: 500 Yes;200 No; 100 not sure
to R: 400 Yes;300 No; 100 not sure
200 only reply Yes to M ;
ask what is the number of student who do not reply either Yes ?
------------ I get 200
答案: 200
思路:
[Tessi] 在 to ”M: 500 Yes “students 中， 有200 only reply Yes to M, 就是说，这200人不reply YES  to M, therefore, they are among the students  "to R: 300 No; 100 not sure"======>
在 ”to R: ;300 No; 100 not sure“ students 中， 有300+100-200students will not reply to M as YES too.
because 在 ”to R: ;300 No; 100 not sure“ 这400 students , don't reply to M as Yes, therefore, the students don't reply YES to either  M or R should be 200


255) the other difficulty:
if each patron will borrow from 1 book to 10 books from the library,
the total number of the books borrowed from the library is 1600
ask if the number is greater than 300?
1) 150 patrons brrow 3or 4books
2) there are 80 patrons borrow 1or 2 ; 150 patrons borrow 3 or 4(not sure of the particular number)
-----------I get 2), I use the maximal possible number.
答案: B
思路:
[Tessi]: 思路是：patrons who borrow  1 or 2 books can maximally borrow 80*2 books
patrons who borrow 3 or 4 can maximally borrow 150*4 books
therefore, the remaining books are 1600-80*2-150*4=..., let us express it as X
then you can divide  x by 10,
you should see if
x/10 + 80 + 150 is greater than 30
[usdusaj] suppose total for 1, 2books x,
suppose total for 1, 2books y,
8045080+450the remain boks is A=1600-x-y. SO 940so total 80+150+94>300.

lt

223: B同252
234: A
252: D
２５４？３００

hawaii2001

谢谢ruthere.
223) 说一个邮递服务项目收基本费 3 元， 然后每个发运的东西价格是19。95 员。问总共发了多少个东西？
  （1）。 发运的东西总价值介于 200 与 225 元之间；
  （2）。 发运的东西总价值介于 185 与 205 元之间；
         （ the figures above are not necessarily correct, but the logic is the same）
这题大侠給讲讲思路好吗?
234题.我选D.
245和247看不懂题意.
252题.我选D.
254题,答案是300还是200, 我准备背这个答案,下周三考.
谢谢各位大侠.

水晶风铃

252 D

hawaii2001

231题,我算得23%, 不知对否?

水晶风铃

234,D

whipwan

234 A

Samson2004

以下是引用whipwan在2003-11-23 14:27:00的发言：
234 A

同意。
231，70％
242，75
252，D

请指教。

[此贴子已经被作者于2003-11-23 16:27:11编辑过]

usdusaj

[Tessi] 在 to ”M: 500 Yes “students 中， 有200 only reply Yes to M, 就是说，这200人不reply YES  to M, therefore, they are among the students  "to R: 300 No; 100 not sure"======>
在 ”to R: ;300 No; 100 not sure“ students 中， 有300+100-200students will not reply to M as YES too.
because 在 ”to R: ;300 No; 100 not sure“ 这400 students , don't reply to M as Yes, therefore, the students don't reply YES to either  M or R should be 200


不大懂得？

yhcui

以下是引用Samson2004在2003-11-23 16:22:00的发言：

同意。
231，70％
242，75
252，D

请指教。

[此贴子已经被作者于2003-11-23 16:27:11编辑过]

同意231  70%