AMC 8 2008 Problem 19

AMC8 2008 年第 19 题

概率★★★☆☆

Eight points are spaced around at intervals of one unit around a 2×2 square, as shown. Two of the 8 points are chosen at random. What is the probability that the two points are one unit apart?

如图所示，八个点绕着一个 2×2 的正方形等间距分布，相邻点的距离均为 1 个单位。从这 8 个点中随机选择其中两个点，则这两点相距一个单位的概率是多少？

A. $\displaystyle \frac{1}{4}$
B. $\displaystyle \frac{2}{7}$
C. $\displaystyle \frac{4}{11}$
D. $\displaystyle \frac{1}{2}$
E. $\displaystyle \frac{4}{7}$

正确答案 · Correct Answer

B

解析 · Solution

解析整理中

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