AMC 8 2015 Problem 11

AMC8 2015 年第 11

概率★★★☆☆
In the small country of Mathland, all automobile license plates have four symbols. The first symbol must be a vowel ( A, E, I, O, or U ), the second and third symbols must be two different letters among the 21 non-vowels in the alphabet, and the fourth symbol must be a digit ( 0 through 9 ). If the symbols are chosen at random subject to these conditions, what is the probability (In fractions) that the plate will read " AMC8 "?
在 Mathland 这个小国家,所有汽车的牌照都有 4 个符号。第一个符号必须是个韵母(A,E,I,O 或 U),第二个和第三个符号必须是 21 个非韵母中不同的两个字母,第四个必须是一个数字 (0 到 9),如果符号都是按照这些规则随机选择的,那么牌照上显示的是"AMC8"概率是多少?
  1. A.122,050\displaystyle \frac{1}{22,050}
  2. B.121,000\displaystyle \frac{1}{21,000}
  3. C.110,500\displaystyle \frac{1}{10,500}
  4. D.12,100\displaystyle \frac{1}{2,100}
  5. E.11,050\displaystyle \frac{1}{1,050}

正确答案 · Correct Answer

B

解析 · Solution

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