Sets A, B, and Chave some elements in common. If 16elements are in both A and B, 17 elements are in both A and C, and 18 elementsare in both B and C, how many elements do all three of the sets A, B, and Chave in common?
(1) Of the 16elements that are in both A and B, 9 elements are also in C.
(2) A has 25elements, B has 30 elements, and C has 35 elements.
条件1是sufficient的，条件2，如果不用列举法，怎样得出sufficient or not?作者: timothyyung 时间: 2011-8-29 21:12
