AMC 8 2020 Problem 21

AMC8 2020 年第 21

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A game board consists of 64 squares that alternate in color between black and white. The figure below shows square P in the bottom row and square Q in the top row. A marker is placed at P. A step consists of moving the marker onto one of the adjoining white squares in the row above. How many 7 -step paths are there from P to Q? (The figure shows a sample path.)
一种游戏板由 64 个黑白相间的方块组成。下图显示了底行中的一个正方形 P 和顶行中的一个正方形 Q。在正方形 P 上放了一个标记,将标记移到上面一行中相邻的一个白色正方形上,这个操作称为一步。从 P 到 Q 有多少种 7 步路径?(图中显示了一种可能的示例路径)。
AMC 8 2020 Problem 21 figure
  1. A.28
  2. B.30
  3. C.32
  4. D.33
  5. E.35

正确答案 · Correct Answer

A

解析 · Solution

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