[求助]GWD10-9

yaskemail

A gardener is going to plant 2 red rosebushes and 2 white rosebushes. If the grdener is to sleect 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

How to do it?

smart

4个位置中取两个位置种red rosebushes,另外两个放white的可能性只有一种。

总的组合有：P(4,4)/[P(2,2)*P(2,2)]=6.分母的意思是因为red rosebushes和white rosebushes是identical的。

所以，概率为：1/6。

crossmoon

agree with Smart