GWD1--Q9求助

chinamyb

    

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

    
不太明白这道题在说什么，请大侠指教~谢谢

chinamyb

    

再加上一道题 谢谢

Q10:

    

A set of numbers has the property that for
any number t in the set, t + 2 is in the set. 
If –1 is in the set, which of the following must also be in the set?

    

 

    

I.                   
-3

    

II.                
1

    

III.              
5

    

 

    

 

    

A.    I only

    

B.    II only

    

C.    I and II only

    

D.    II and III only

    

E.    I, II, and III

charismale

以下是引用chinamyb在2008-5-4 14:20:00的发言：

 

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

 
不太明白这道题在说什么，请大侠指教~谢谢

两红两白，随机摆放成一排，问俩红的在中间的概率。

charismale

以下是引用chinamyb在2008-5-4 14:31:00的发言：

 

再加上一道题 谢谢

Q10:

 

A set of numbers has the property that for
any number t in the set, t + 2 is in the set. 
If –1 is in the set, which of the following must also be in the set?

 

 

I.                   
-3

 

II.                
1

 

III.              
5

 

 

 

A.    I only

 

B.    II only

 

C.    I and II only

 

D.    II and III only

 

E.    I, II, and III

一个数的集合有这样的属性：

对于任何一个集合中的数t，t+2也在这个集合中

已知-1在集合里面，问下面哪个数也在集合里面？

chinamyb

明白了 十分感谢！！！