[讨论]04年06月数学JJ讨论稿第5篇(91-110)

horsefish

91. 如图左边这半个三角形直角等腰，求右边那个钝角三角形的面积。
horsefish:25(根号3-1)/2
[upload=jpg]UploadFile/2004-6/200462325619533.jpg[/upload]
思路:角BCA=30度,所以AC=10;BC=根号(AC^2-5^2)-5=5根号3-5;; 面积=0.5(5*BC)

92、PS偶的第一题：下面那个分数最小(C)
A)1/100   B) 1/0.001   C) 1/500   D) 1/0.005  E) 1/20  
horsefish:C

93.PS:Y/X的绝对值<1，以下那项正确？ （D）
A) X/Y的绝对值<1
B) Y/X<1
C) (Y+1)/(X+1)<1
D) (Y的绝对值+1)/(X的绝对值＋1)
horsefish:B和 D(如果表达式<1) 请大家讨论

94、DS：There are kinds of cars with colors of white, blue and red. The models are large size, middle size and small size. Ask: how many white cars with large size. (C)
A) there are 31 white cars, 17 blue cars and 12 red cars.
B) the large size models have no blue and red cars; there are less middle size and small size cars than large size cars.
horsefish:同意

95 average salary of employees —— x company:   28129   y company:  36518
      average salary of employees for x company and y company combined?
1)      x company has 1200 more employees than y company
2)      forget

96、美国人口，45-60年龄段，1955-1980人口变化46-60million，30-35年龄段36-35million, 求45-60年龄段增长的幅度与30-35年龄段下降的幅度之比？
horsefish: 14/46:1/36= 14*36 / 46

97、一个园上7个点，以这些点为顶点可以组成三角形与四边形个数之比
horsefish:1

98、下面那组数的方差最大？A 20  20  30   B 20  25  30   C  20   20  40   …..
horsefish:C

思路:同加/减某数, 方差不变;同乘除某数n,方差变化n倍. 所以可以按A:0, 0, 10 B: 0,5,10 C: 0,0,20 分别计算方差.

99、三个计算机价格，A>M? ( AVERAGE > MEAN)
    1) M小于最大数与最小数的平均数
    2) 最大数比A大250，最小数比A小150
horsefish(注意题目的mean应该是median)

100   My first one: PS Which one is equal to 40% of 40% of 0.4?
horsefish:0.4*40%*40%

101  S. Which one has the greatest standard deviation:
A: 20, 20, 30  B: 25, 30, 35  C: 35, 40, 45  D: 20, 30, 30  E: ….
horsefish:A,D

102    PS. Linda walked at a constant speed of r, and passed one point of the city board at 12:00 at noon. Sue also walked at a constant speed and passed the same point at 1:00 that afternoon. How far Linda walked away from that point when she was compassed by Sue?
      A. r B. 2/3 r        C 3/2 r          D 2r       E: 3r
horsefish:A

103 AB//CD, AB=BD, PBD is a right angle, how long is AB?
1.     B=10
2.     DB=30 degree

104   S what is 0.01 percentage of 45,258?
horsefish:4.5258
105  1-0.000001 与下面哪个值相等？选项记不太清了

105-1 告诉长方形的周长为560，对角线是200，问面积? 19200
horsefish:同意

106  一个检验员查次品，说非次品的是次品的24倍，问次品率？我答1/25
horsefish:同意

107  一个圆不按次序划分10度，20，30，40，50，60，70，80，说各点连起来成一个八边形，问这个八边形的最大可能的内角是多少？我不明白，选项有 A 155 B160 C 165 D 170 E175 我瞎选了一个160
horsefish:C
思路:如图所示(马鱼随便做的, 没比例)[attachimg]17271[/attachimg]
角ABC是八边形中的内角,三角形AOB是等腰三角形>>>OAB=OBA=(180-AOB)/2,
同理OBC=BCO=(180-BOC)/2
>>>ABC=ABO+CBO=(180-AOB)/2+(180-BOC)/2,
如果要ABC最大, 则AOB+BOC=最小,即AOB+BOC=30, >>>ABC=165

108 说10^50-74若以10为base 表示成notion的形式，问这些数的和是下面哪个？好像有424，434，324什么的，我实在记不起来了。反正我不会，瞎选了一个

horsefish:48*9+2+6(题目求10^50-74的各个位数的总和)

思路: 10^2=100,10^3=1000,...>>>10^50=1000....0(共50个0),减去74说明前面48位都是9,最后两位尾数是26.

109   r+1/s=? 可能做的不好，电脑气疯了，给我一个很简单的题，好像是二十几题的时候

110   0.5/(1/8+0.25)=? 我的第一题 4/3
horsefish:同意

[此贴子已经被作者于2004-7-5 7:27:23编辑过]

miaoyin_tx

Horsefish MM, why do you choose E on #92?

(C)1/500=0.002 (E)1/20=0.05

horsefish

以下是引用miaoyin_tx在2004-6-23 4:34:00的发言：

Horsefish MM, why do you choose E on #92?

(C)1/500=0.002 (E)1/20=0.05

谢谢, 改正了. JJ一多就忙中出错

msryiyg2

horsefish, why the serial no in 04年06月数学JJ讨论稿 is different from 04年6月math机经滚动总结, really confused? could u please revised it to make it clear.  tks very much!

我爱宝宝

是我的问题，我应该先出鱼mm一段时间汇总。

但是我速度不足够快，先出她的时间实在，咳咳，有限。所以，出现问题了。

我来改正汇总吧。

[此贴子已经被作者于2004-6-24 12:31:22编辑过]

我爱宝宝

95 average salary of employees —— x company:   28129   y company:  36518

      average salary of employees for x company and y company combined?

1)      x company has 1200 more employees than y company

2)      forget

96、美国人口，45-60年龄段，1955-1980人口变化46-60million，30-35年龄段36-35million, 求45-60年龄段增长的幅度与30-35年龄段下降的幅度之比？

97、一个园上7个点，以这些点为顶点可以组成三角形与四边形个数之比

98、下面那组数的方差最大？A 20  20  30   B 20  25  30   C  20   20  40   …..

99、三个计算机价格，A>M? ( AVERAGE > MEAN)

    1) M小于最大数与最小数的平均数
    2) 最大数比A大250，最小数比A小150

100   My first one: PS Which one is equal to 40% of 40% of 0.4?

101  S. Which one has the greatest standard deviation:

A: 20, 20, 30  B: 25, 30, 35  C: 35, 40, 45  D: 20, 30, 30  E: ….

102    PS. Linda walked at a constant speed of r, and passed one point of the city board at 12:00 at noon. Sue also walked at a constant speed and passed the same point at 1:00 that afternoon. How far Linda walked away from that point when she was compassed by Sue?

      A. r B. 2/3 r        C 3/2 r          D 2r       E: 3r

103 AB//CD, AB=BD, PBD is a right angle, how long is AB?

1.     B=10

2.     DB=30 degree

104   S what is 0.01 percentage of 45,258?

miaoyin_tx

Horsefish MM, 第94题，M代表Median罢？因为Average就是Mean

lammyvicky

  

102    PS. Linda walked at a constant speed of r, and passed one point of the city board at 12:00 at noon. Sue also walked at a constant speed and passed the same point at 1:00 that afternoon. How far Linda walked away from that point when she was compassed by Sue?

      A. r B. 2/3 r        C 3/2 r          D 2r       E: 3r

明天考，请问有人知道这题是再问什么吗？

Dani

I think No.93, C is correct, too. Who can explain it to me, please?

tianwan

96、美国人口，45-60年龄段，1955-1980人口变化46-60million，30-35年龄段36-35million, 求45-60年龄段增长的幅度与30-35年龄段下降的幅度之比？
horsefish:14:1

14/46   /    1/36= 14*36 / 46