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The letters R, W, S, T, M, and P are to be arranged from left to right in a sequence such that each of the 6 letters occurs exactly once. For example, PMRSTW is one such sequence. Of all possible sequences of this type, how many have S as the left-most letter and T as the right-most letter?
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· 相关考点
6.3.4 排列
6.3.4 排列
以上解析由 考满分老师提供。
