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?
~$\frac{1}{12}$~
~$\frac{1}{6}$~
~$\frac{1}{5}$~
~$\frac{1}{3}$~
~$\frac{1}{2}$~
1)总共有4×3×2=24种种法
2)如果中间两棵是红色两种种法×第一和第四个坑为白色共两种种法=4种种法
3)2)/1)=1/6
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