2#
大 中
小 發表於 2015-11-10 11:00 PM (第 3061 天)
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(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?