第二题:What if not all money need be invested? 可这样理解：

来源: 皆兄弟也 于 2010-09-08 10:37:04 [] [博客] [旧帖] [给我悄悄话] 阅读数 : (271 bytes)
回答: 回复：回复：回复：请教解数学题。 由 guest1000 于 2010-09-07 19:51:53

Investing 16 thousand dollars to 5 possible opportunities. To some of opportunities, 0 could be invested.

The fifth opportunity is investor's wallet. There is still some money in investor's wallet, not be invested yet.

So result is C(16+5-1,5-1) = C(20,4)

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