ChaseDream

标题: tt-1-2,7,8,9,10,24,30 [打印本页]

作者: allen0018    时间: 2006-7-10 23:38
标题: tt-1-2,7,8,9,10,24,30

谢谢大家,我今天做了tt-1有数学题不明白,真不明白

希望大家帮忙

Q2:

A certain roller coaster has 3 cars, and a passenger is equally likely to ride in any 1 of the 3 cars each time that passenger rides the roller coaster.  If a certain passenger is to ride the roller coaster 3 times, what is the probability that the passenger will ride in each of the 3 cars?

 

A.        0

B.        1/9

C.        2/9

D.       1/3

E.        1

Answer: c


作者: allen0018    时间: 2006-7-10 23:42

Q3:

If x and y are positive, is 4x > 3y?

(1)     x > y - x

(2)     x/y < 1

e

像这样比较大小的,到底应该怎么做???

每次都稀里糊涂

每次都心惊胆颤


作者: allen0018    时间: 2006-7-10 23:46

Q9:

A gardener is going to plant 2 red rosebushes and 2 white rosebushes.  If the gardener is to select each of the bushes at random, one at a time, and plant them in a row, what is the probability that the 2 rosebushes in the middle of the row will be the red rosebushes?

 

A.      1/12

B.      1/6

C.      1/5

D.     1/3

E.      1/2   key:b

我选的是d

我怀疑这2个白花布一样?

我是c1-3;   答案 怎么来的?


作者: allen0018    时间: 2006-7-10 23:49

Q18:

 

                   x

 

 

   x                 2 in          x

                                                          

 

 

      

             x

 

 

 

 

 

 

 

 

 

 


                                        

                                    Note: Figure not drawn to scale.

 

The figure shows a square patio surrounded by a walkway of width x meters.  If the area of the walkway is 132 square meters and the width of the patio is 5 meters greater than the width of the walkway, what is the area of the patio, in square meters?

 

A.      56

B.      64

C.      68

D.     81

E.      100

这题说的是什么意思???

答案是b

我发布上图片,怎么办?


作者: allen0018    时间: 2006-7-10 23:51

Q24:

If w and c are integers, is w > 0?

(1)     w + c > 50

(2)     c > 48

                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

e

我想问大家不等式同向加减的知识点


作者: yaoyao99    时间: 2006-7-11 00:00

Please please separate your questions into individual posts and add a good title for each one (e.g. 涛涛 GWD-xx-yy)

Please also search for existing discussions before you post your questions:

http://forum.chasedream.com/dispbbs.asp?boardID=22&ID=176560&page=1

[原创]*GWD数学*讨论贴集锦!  by maki        点击此处查看
涵盖了涛涛31套将近一半的数学讨论


作者: 顾风    时间: 2006-7-11 09:33
以下是引用allen0018在2006-7-10 23:38:00的发言:

谢谢大家,我今天做了tt-1有数学题不明白,真不明白

希望大家帮忙

Q2:

A certain roller coaster has 3 cars, and a passenger is equally likely to ride in any 1 of the 3 cars each time that passenger rides the roller coaster.  If a certain passenger is to ride the roller coaster 3 times, what is the probability that the passenger will ride in each of the 3 cars?

 

 

A.        0

B.        1/9

C.        2/9

D.       1/3

E.        1

Answer: c

c(1,3)*c(1,2)/3^3,即坐一1次,坐二一次,坐三一次相乘后除以三的三次方


作者: 顾风    时间: 2006-7-11 09:34
以下是引用allen0018在2006-7-10 23:42:00的发言:

Q3:

If x and y are positive, is 4x > 3y?

(1)     x > y - x

(2)     x/y < 1

e

像这样比较大小的,到底应该怎么做???

每次都稀里糊涂

每次都心惊胆颤

条件1为 2x>y,即 4x>2y

条件2为 x,y同正或同负,如果同正,x<y,如果同负 x>y

所以得不出结论


作者: 顾风    时间: 2006-7-11 09:36
以下是引用allen0018在2006-7-10 23:46:00的发言:

Q9:

A gardener is going to plant 2 red rosebushes and 2 white rosebushes.  If the gardener is to select each of the bushes at random, one at a time, and plant them in a row, what is the probability that the 2 rosebushes in the middle of the row will be the red rosebushes?

 

 

A.      1/12

B.      1/6

C.      1/5

D.     1/3

E.      1/2   key:b

我选的是d

我怀疑这2个白花布一样?

我是c1-3;   答案 怎么来的?

是这样做的,不要用组合

a,b,b,a; a,b,a,b; a,a,b,b;

b,a,a,b;b,a,b,a; b,b,a,a;所以是 b,understand?


作者: 顾风    时间: 2006-7-11 09:43
以下是引用allen0018在2006-7-10 23:49:00的发言:

Q18:

 

 

                                        

                                    Note: Figure not drawn to scale.

 

 

The figure shows a square patio surrounded by a walkway of width x meters.  If the area of the walkway is 132 square meters and the width of the patio is 5 meters greater than the width of the walkway, what is the area of the patio, in square meters?

 

 

A.      56

B.      64

C.      68

D.     81

E.      100

这题说的是什么意思???

答案是b

我发布上图片,怎么办?

w = 5+x

s = (5+x+2x)*x+(5+x)*x*2+(5+x+2x)*x = 132

所以 42+48+42 = 132 , x=3

即sw =64


作者: 顾风    时间: 2006-7-11 09:45
以下是引用allen0018在2006-7-10 23:51:00的发言:

Q24:

If w and c are integers, is w > 0?

(1)     w + c > 50

(2)     c > 48

                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

e

我想问大家不等式同向加减的知识点

当然不能确定, when c= 100时 w>-50

    when c = 49时, w>1

so, choose e


作者: windlove    时间: 2006-8-27 10:05

to Q9.

4 rosebushes, so the total possibility is Permutation(4,4), ie, there are 24 possible outcomes to order the place of them,

then for the red rosebushes in the middle, there are two outcomes as r1 r2 or r2 r1 in the middel of the place, and for the white ones, there are two outcomes as well, ie, w1 r r w2, w2 r r w1 , so the numerator should be 2*2, and denominator should be 24. 4/24=1/6


作者: yaoyao99    时间: 2006-8-27 12:07

http://forum.chasedream.com/dispbbs.asp?boardID=22&ID=184062&page=1

1-2    http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1702136&id=180094&skin=0
         http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1711358&id=180995&skin=0
          http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1673068&id=176916&skin=0
1-7    http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1711358&id=180995&skin=0
1-8    http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1711358&id=180995&skin=0
1-9    http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1711358&id=180995&skin=0
1-10  http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1702155&id=180097&skin=0
         http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1711358&id=180995&skin=0
1-24  http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1711358&id=180995&skin=0
1-30  http://forum.chasedream.com/dispbbs.asp?BoardID=22&ID=181383
         http://forum.chasedream.com/dispbbs.asp?BoardID=22&ID=179869
         http://forum.chasedream.com/dispbbs.asp?BoardID=22&ID=176919
         http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1711358&id=180995&skin=0


作者: hollycheng    时间: 2006-12-1 03:05
发贴心情
以下是引用allen0018在2006-7-10 23:46:00的发言:

Q9:

A gardener is going to plant 2 red rosebushes and 2 white rosebushes.  If the gardener is to select each of the bushes at random, one at a time, and plant them in a row, what is the probability that the 2 rosebushes in the middle of the row will be the red rosebushes?

A.      1/12

B.      1/6

C.      1/5

D.     1/3

E.      1/2   key:b

我选的是d

我怀疑这2个白花布一样?

我是c1-3;   答案 怎么来的?

是这样做的,不要用组合

a,b,b,a; a,b,a,b; a,a,b,b;

b,a,a,b;b,a,b,a; b,b,a,a;所以是 b,understand?

但是如果将两个红rosebushes作为个整体来看,这两个放在中间的可能性不就是1/3了吗?不知怎么解


作者: 不喝水的鱼    时间: 2006-12-20 18:31

楼上MM没有看清楚哦?


作者: wanghan114    时间: 2007-7-23 21:34
怎么没有第7题???
作者: ukyo    时间: 2008-1-1 03:05
关于Q9可以把红房看成a1 a2白房是b1 和b2那么就可以有4可能在中间b1 a1 a2 b2;b2 a1 a2 b1;b1 a2 a1 b2;b2 a2 a1 b1;
由于随机选择所以总共24种可能,4/24这是我的理解

作者: xlyun    时间: 2008-2-25 00:27

我和十七楼这种思路差不多.嘿嘿,我认为是,先全排列A44=24因为两个RR相同两个WW相同,所以要除二,即12种不同的排法,而中间是两个RR的不同种排法有2种,所以概率为2\12=1\6


作者: Amber789    时间: 2008-7-15 06:56
以下是引用allen0018在2006-7-10 23:46:00的发言:

Q9:

A gardener is going to plant 2 red rosebushes and 2 white rosebushes.  If the gardener is to select each of the bushes at random, one at a time, and plant them in a row, what is the probability that the 2 rosebushes in the middle of the row will be the red rosebushes?

 

 

 

A.      1/12

B.      1/6

C.      1/5

D.     1/3

E.      1/2   key:b

我选的是d

我怀疑这2个白花布一样?

我是c1-3;   答案 怎么来的?

(p22*p22)/p44=4/24=1/6
作者: perrier    时间: 2009-5-24 11:48
以下是引用allen0018在2006-7-10 23:46:00的发言:

Q9:

A gardener is going to plant 2 red rosebushes and 2 white rosebushes.  If the gardener is to select each of the bushes at random, one at a time, and plant them in a row, what is the probability that the 2 rosebushes in the middle of the row will be the red rosebushes?

 

 

A.      1/12

B.      1/6

C.      1/5

D.     1/3

E.      1/2   key:b

我选的是d

我怀疑这2个白花布一样?

我是c1-3;   答案 怎么来的?

我的解题方法:

第一朵取到白色的概率:2/4

第二朵取到红色的概率:2/3

第三朵取到红色的概率:1/2

第四朵取到白色的概率:1(条件概率)

四者相乘=1/6


作者: yoshimihoku    时间: 2010-7-6 08:53
Please please separate your questions into individual posts and add a good title for each one (e.g. 涛涛 GWD-xx-yy)
Please also search for existing discussions before you post your questions:
http://forum.chasedream.com/dispbbs.asp?boardID=22&ID=176560&page=1
[原创]*GWD数学*讨论贴集锦!  by maki        点击此处查看
涵盖了涛涛31套将近一半的数学讨论
-- by 会员 yaoyao99 (2006/7/11 0:00:00)





题号完全对不上!!!我痛苦着呢,只能搜索!
作者: jingle0915    时间: 2010-7-29 19:22
谢谢!
作者: jingle0915    时间: 2010-7-29 19:31
明白了。你真聪明!
作者: ava_dove    时间: 2010-7-29 19:46
to Q9
这个题因为是算概率,古典概型的好处就是不论你认为元素相同或不同都可以做

如果认为4块布均为不同的元素,红的在中间白的在两边一共有2*2两种,除以4块布的全排列就可以了,所以是 2*2/P(4,4)

如果认为同颜色的两块相同,分子只可能有1种情况,而分母是4块布的全排列再去除序,所以是 1/[P(4,4)/P(2,2)/P(2,2)]=1/6
作者: mansontears    时间: 2011-3-2 05:41
以下是引用allen0018在2006-7-10 23:46:00的发言:
Q9:
A gardener is going to plant 2 red rosebushes and 2 white rosebushes.  If the gardener is to select each of the bushes at random, one at a time, and plant them in a row, what is the probability that the 2 rosebushes in the middle of the row will be the red rosebushes?




A.      1/12
B.      1/6
C.      1/5
D.     1/3
E.      1/2   key:b

我选的是d
我怀疑这2个白花布一样?
我是c1-3;   答案 怎么来的?

是这样做的,不要用组合
a,b,b,a; a,b,a,b; a,a,b,b;
b,a,a,b;b,a,b,a; b,b,a,a;所以是 b,understand?
-- by 会员 顾风 (2006/7/11 9:36:00)



我是这样做的,不知道方法是否正确
按照白红红白的顺序走的话,被选概率依次为1/4,1/3,1/2,1.
所以中间两个的概率应该是1/3*1/2=1/6...
作者: mansontears    时间: 2011-3-2 05:45
还有,是不是算这个题完全不需要考虑颜色的?
因为他们都是2V2 的,所以哪个都一样!~~
作者: caoqin1981    时间: 2011-9-21 17:44
Q9:

A gardener is going to plant 2 red rosebushes and 2 white rosebushes.  If the gardener is to select each of the bushes at random, one at a time, and plant them in a row, what is the probability that the 2 rosebushes in the middle of the row will be the red rosebushes?
A.      1/12

B.      1/6

C.      1/5

D.     1/3

E.      1/2   key:b

想问一下,这道题怎么用排列组合公式做出来?
作者: wellizsm    时间: 2011-9-21 19:08
Q24 同向不等式相加 不等号不变 如题可得w+c+c>50+48 也就是w+2c>98
不同向不等式相减 不等号同被减式 如果w+c>50 c<48 那么w+c-c>50-48 也就是w>2
同向相减和不同向相加 似乎得不出什么有效的结论
作者: 山虎君    时间: 2011-11-21 18:13
标题: GWD01 Q9解答
今天做Q9被卡住了,看了大家的思路后,我想到了一个简单的式子,不知可行否:

由于2红2白的组合是确定的,所以需要在四个位置中选两个红的,这样剩下的两个位置自然就是白的,反之先选白的也一样,所以总数为C(4,2)=6.


题目要求中间两个为红的,所以就都是红的,只有这一种情况,即C(2,2)=1.


于是,概率=C(2,2)/C(4.2)=1/6.


希望能看懂”组合“的表述。
作者: 方可恨悠悠    时间: 2012-5-12 22:50
话说第7题呢。。。

感觉不难但是算了好几次也得不出正确答案。。。。
作者: hellohappywyy    时间: 2017-11-3 22:21
感谢分享!               
作者: WWVV    时间: 2020-4-8 18:35
allen0018 发表于 2006-7-10 23:46
Q9:A gardener is going to plant 2 red rosebushes and 2 white rosebushes.&nbsp; If the gardener is to ...

看一下!               




欢迎光临 ChaseDream (https://forum.chasedream.com/) Powered by Discuz! X3.3