The Six Sigma Black Belt should know factorials, permutations and combinations, and how to use these in commonly used probability distributions.

六西格玛黑带应了解析因、置换、合并等方法，以及它们在概率分布中的一般应用。

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Permutations and Combinations are important basis in mathematics. They are often used, especially in Probability Statistics.

排列组合是数学的一个重要基础，特别是在《概率统计》学中经常要用到。

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