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# [學科討論] 數學問題

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## 數學問題

(a) How many ways to distribute 10 books to 4 boys (note that the books are different)?
(b) How many ways to distribute 10 books to 4 boys so that the oldest boy gets 4 books and the other two boys get 2 books each?
(c) How many ways to distribute 10 candies to 4 boys (note that the candies are indistinguishable)?
(d) How many ways to distribute 10 candies to 4 boys so that the oldest boy gets at least 2 candies and every boy gets at least one candy?

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 mtutor15 初級學徒 發短消息 加為好友 當前離線 2# 大 中 小 發表於 2015-11-10 11:00 PM (第 1488 天) 只看該作者 (a) There are 4 options for the owner of each book, so the total ways = 4 x 4 x ... (b) Denote the four boys be A, B, C and D. Take A as the oldest boy, give 4 books to A first, then 2 to B, 2 to C and the remaining 2 to D. Order of the books does not matter. (c) Hint: 1 + 1 + 1 + 7 = 10, 0 + 0 + 0 + 10 = 10, ... , the message here is the "+". (d) The problem can be simplified to sharing 5 candies among 4 boys. Why? mtutor15@App 17 UID388245 帖子8 精華0 積分1 閱讀權限5 在線時間10 小時 註冊時間2015-9-28 最後登錄2015-11-12  查看詳細資料 TOP
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