Question

三张牌标有 X，另外两张牌标有 O。将这五张牌随机排成一行。排列读作 XOXOX 的概率是多少？

Three tiles are marked X and two other tiles are marked O. The five tiles are randomly arranged in a row. What is the probability that the arrangement reads XOXOX?

$\dfrac{1}{12}$

$\dfrac{1}{10}$

$\dfrac{1}{6}$

$\dfrac{1}{4}$

$\dfrac{1}{3}$

答案：B

知识点：基本概率组合

难度评级：1280

解答：

三个 X 的位置可以是 $\binom{5}{3} = 10$ 种等可能选择，其中只有一种位置选择产生 XOXOX，所以概率为 $\dfrac{1}{10}$ 。

所以正确答案是 B。

The three X positions can be any of $\binom{5}{3} = 10$ equally likely choices, and exactly one of them produces XOXOX. So the probability is $\dfrac{1}{10}.$

Thus, the correct answer is B.

2005 AMC 10A 第 9 题

答案：B

难度评级：1280

解答：

其他年份的第 9 题