我终于想明白了为什么非洲人没驯化（斑）马 - 未名空间MITBBS历史存档

我终于想明白了为什么非洲人没驯化（斑）马# Joke - 肚皮舞运动

a*g2010-04-08 07:04

1 楼

1.At Marsh Mel Low Middle School 34 students play soccer, 36 students play
football and 29 students play basketball. Of these students 15 play both
soccer and football, 18 play both basketball and football and 13 play both
soccer and basketball. What is the smallest possible number of students that
play all three sports?
2. If x and y are two triangular numbers less than 100 that when added,
produce a sum that is a square number, what is the largest possible value of
x or y?
3. Suppose that six brothers (George, John, Thomas, Fred, Andrew, Martin)
each roll a fair 6-sided die. At least three of them have rolled an even
number. What is the probability that John, Fred and Martin have each rolled
an even number? Express your answer as a common fraction.

y*r2010-04-08 07:04

2 楼

【以下文字转载自 History 讨论区】
发信人: happyboar (We must continue our struggle), 信区: History
标题: 我终于想明白了为什么非洲人没驯化（斑）马
发信站: BBS 未名空间站 (Thu Apr 8 17:08:43 2010, 美东)
为什么非洲人没驯化马，斑马，或者任何类似的骑乘动物？我经过在史版，军版长期的
文献考察，发现了一个可以自圆其
说的论证。
（1）人类进行发明创造，最大的驱动力是战争。为了民用目的而发明，虽然不是没有
，但没有为了军用目的积极迫切。
（2）为什么非洲人没驯化战马呢？一言以蔽之：骑兵的战略机动能力太差，比不过步
兵，非洲人为什么费力不讨好呢？
（3）为什么亚洲，欧洲人广泛使用骑兵呢？首先，白人，黄人长跑能力稍逊，与马相
比优势不明显。更重要的，人类长跑
项目上对马的优势，在天气炎热的情况下最能体现。非洲草原上，黑人健步如飞，日行
百里，战马虽然冲刺能力强，可是
跑不了几里路，就吐着舌头喘气。还没上战场，先自己热死了。
大家说，我这个论证能通过peer-review么？
参考文献
（

B*12010-04-08 07:04

3 楼

1.At Marsh Mel Low Middle School 34 students play soccer, 36 students play
football and 29 students play basketball. Of these students 15 play both
soccer and football, 18 play both basketball and football and 13 play both
soccer and basketball. What is the smallest possible number of students that
play all three sports?
Since there are 18 play both basketball and football and 13 play both soccer
and basketball, but there there are 29 students playing basketball, then at
least there are 2 person who play all three sports.

o*y2010-04-08 07:04

4 楼

至少搞几张图俩个表吧，机器人写paper都知道。

【在 y**********r 的大作中提到】

: 【以下文字转载自 History 讨论区】
: 发信人: happyboar (We must continue our struggle), 信区: History
: 标题: 我终于想明白了为什么非洲人没驯化（斑）马
: 发信站: BBS 未名空间站 (Thu Apr 8 17:08:43 2010, 美东)
: 为什么非洲人没驯化马，斑马，或者任何类似的骑乘动物？我经过在史版，军版长期的
: 文献考察，发现了一个可以自圆其
: 说的论证。
: （1）人类进行发明创造，最大的驱动力是战争。为了民用目的而发明，虽然不是没有
: ，但没有为了军用目的积极迫切。
: （2）为什么非洲人没驯化战马呢？一言以蔽之：骑兵的战略机动能力太差，比不过步

B*12010-04-08 07:04

5 楼

2. If x and y are two triangular numbers less than 100 that when added,
produce a sum that is a square number, what is the largest possible value of
x or y?
Triangular numbers less than 100: 1,3, 6, 10,15,21,28,36,45,55,66,78,91
A squre number less than 200: 1, 4, 9, 16,25,36,49,64,81,100,121,144,169,196
Apparently 45 + 55 =100. So we know at least 55 is one possible choice.
Can we go any higher? Let's try 91. 196 is out. 169-91 = 78
Bingo.
The answer is 91.

v32010-04-08 07:04

6 楼

这个是有道理的。

【在 y**********r 的大作中提到】

: 【以下文字转载自 History 讨论区】
: 发信人: happyboar (We must continue our struggle), 信区: History
: 标题: 我终于想明白了为什么非洲人没驯化（斑）马
: 发信站: BBS 未名空间站 (Thu Apr 8 17:08:43 2010, 美东)
: 为什么非洲人没驯化马，斑马，或者任何类似的骑乘动物？我经过在史版，军版长期的
: 文献考察，发现了一个可以自圆其
: 说的论证。
: （1）人类进行发明创造，最大的驱动力是战争。为了民用目的而发明，虽然不是没有
: ，但没有为了军用目的积极迫切。
: （2）为什么非洲人没驯化战马呢？一言以蔽之：骑兵的战略机动能力太差，比不过步

t*o2010-04-08 07:04

7 楼

你老要在这里开堂授课吧。。。

of
196

【在 B******1 的大作中提到】

: 2. If x and y are two triangular numbers less than 100 that when added,
: produce a sum that is a square number, what is the largest possible value of
: x or y?
: Triangular numbers less than 100: 1,3, 6, 10,15,21,28,36,45,55,66,78,91
: A squre number less than 200: 1, 4, 9, 16,25,36,49,64,81,100,121,144,169,196
: Apparently 45 + 55 =100. So we know at least 55 is one possible choice.
: Can we go any higher? Let's try 91. 196 is out. 169-91 = 78
: Bingo.
: The answer is 91.

z*n2010-04-08 07:04

8 楼

简直是一腚的道理啊。

【在 v3 的大作中提到】

: 这个是有道理的。

A*s2010-04-08 07:04

9 楼

play
both
both
students that
2
added,
value of
78 and 91
Martin)
even
8/42

【在 a*****g 的大作中提到】

: 1.At Marsh Mel Low Middle School 34 students play soccer, 36 students play
: football and 29 students play basketball. Of these students 15 play both
: soccer and football, 18 play both basketball and football and 13 play both
: soccer and basketball. What is the smallest possible number of students that
: play all three sports?
: 2. If x and y are two triangular numbers less than 100 that when added,
: produce a sum that is a square number, what is the largest possible value of
: x or y?
: 3. Suppose that six brothers (George, John, Thomas, Fred, Andrew, Martin)
: each roll a fair 6-sided die. At least three of them have rolled an even

i*a2010-04-08 07:04

10 楼

其實我覺得是因為非洲人 gg 太長, 騎馬不方便

B*12010-04-08 07:04

11 楼

3. Suppose that six brothers (George, John, Thomas, Fred, Andrew, Martin)
each roll a fair 6-sided die. At least three of them have rolled an even
number. What is the probability that John, Fred and Martin have each rolled
an even number? Express your answer as a common fraction.
Since "At least three of them have rolled an even number", let's do it one
step at a time.
If all 6 dices are even, there is only one way to do it and there is one way
the three brothers have all even.
If 5 dices are even, there are 6 ways to do it and there are 3 ways the
three brothers have all even.
If 4 dices are even, there are 15 ways to do it and there are 3 ways the
three brothers have all even.
If 3 dices are even, there are 20 ways to do it and only one way the three
brothers have all even.
8/42 = 4/21 is the answer.

s*l2010-04-08 07:04

12 楼

非洲骑马要是碰上狮子了人跑不过马就被狮子吃了，跑得过马要马作甚，所以不必驯化。

【在 i****a 的大作中提到】

: 其實我覺得是因為非洲人 gg 太長, 騎馬不方便

a*g2010-04-08 07:04

13 楼

Thanks a lot!先顶再好好学习。

s*y2010-04-08 07:04

14 楼

Very youcai!

【在 y**********r 的大作中提到】

: 【以下文字转载自 History 讨论区】
: 发信人: happyboar (We must continue our struggle), 信区: History
: 标题: 我终于想明白了为什么非洲人没驯化（斑）马
: 发信站: BBS 未名空间站 (Thu Apr 8 17:08:43 2010, 美东)
: 为什么非洲人没驯化马，斑马，或者任何类似的骑乘动物？我经过在史版，军版长期的
: 文献考察，发现了一个可以自圆其
: 说的论证。
: （1）人类进行发明创造，最大的驱动力是战争。为了民用目的而发明，虽然不是没有
: ，但没有为了军用目的积极迫切。
: （2）为什么非洲人没驯化战马呢？一言以蔽之：骑兵的战略机动能力太差，比不过步

a*g2010-04-08 07:04

15 楼

我也苯的可以，花了2小时才想明白第一题。第二，第三还在思考中。

【在 a*****g 的大作中提到】

: Thanks a lot!先顶再好好学习。

w*r2010-04-08 07:04

16 楼

赞文献引用

a*g2010-04-08 07:04

17 楼

第二题，请问为什么有78？谢谢

【在 A******s 的大作中提到】

:
: play
: both
: both
: students that
: 2
: added,
: value of
: 78 and 91
: Martin)