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?
~$\frac{1}{12}$~
~$\frac{1}{6}$~
~$\frac{1}{5}$~
~$\frac{1}{3}$~
~$\frac{1}{2}$~
在四个位置中选出2个位置(无顺序关系)给两列红玫瑰,一共是 C(4,2)结果是6,所以中间都是红玫瑰的概率是1/6.
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