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Number of outcomes = ?[[0]]

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Suppose $\\var{a}$ people take part in a race. How many different outcomes does the race have, assuming that there are no ties? This includes all $\\var{a}$ positions.

", "tags": ["checked2015", "combinatorics", "MAS1701", "MAS2216", "number of ways of ordering a finite set", "ordering", "permutations", "sc"], "rulesets": {}, "preamble": {"css": "", "js": ""}, "type": "question", "metadata": {"notes": "

7/02/2013:

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Finished first draft. Need a description and perhaps more tags. Included an sc tag.

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There are $\\var{a}$ choices for who comes first.

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There are therefore $\\var{a-1}$ choices for whoever comes second and so on. 

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So there are $\\var{a}\\times \\var{a-1}\\times \\cdots\\times1=\\var{a}!=\\var{ans}$ ways in which the race can finish.

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