Question

一个抽屉里有红、绿、蓝、白四种颜色的袜子，每种颜色至少 $2$ 只。至少要从抽屉里取出多少只袜子，才能保证有一双同色袜子？

A drawer contains red, green, blue, and white socks with at least $2$ of each color. What is the minimum number of socks that must be pulled from the drawer to guarantee a matching pair?

$3$

$4$

$5$

$8$

$9$

答案：C

知识点：抽屉原理

难度评级：720

解答：

为了尽量延迟出现同色一双，最多可以先取出每种颜色各一只袜子。

一共有 $4$ 种颜色，因此取出四只时仍可能没有同色一双。

再取一只就必然与其中一种颜色配成一双，所以需要 $4 + 1 = 5$ 只。

所以正确答案是 C。

To maximize the number of socks, we want to grab as many single socks as possible before getting a pair.

There are $4$ colors, which means that we can draw one sock of each color before drawing a pair.

This means that it takes at least $4 + 1 = 5$ socks to be drawn before a pair is guaranteed.

Thus, C is the correct answer.

2010 AMC 10B 第 3 题

答案：C

难度评级：720

解答：

其他年份的第 3 题