GWD1-Q9:

cjyc1

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

 

 

答案是B，我的答案是A（问题在于2个红玫瑰和2个白玫瑰是否有区别）

G0606

分母24，无异议

两红在中间，两种排法

两白在两边，两种排法

2*2=4

4/24

cjyc1

多谢啊！