这种题目没有公式,只有学会思路举一反三。
这道题目两种做法,
做法1. 至少选一本的话就是所有的情况减去一本都没选到Fashion的情况,那么就是1-3本都是体育的概率: 1-【C(4,3)/C(8,3)】=13/14
做法2,至少一本Fashion,你就把分别是1时尚2本体育,2本时尚1本体育,3本时尚的概率相加:答案做出来是一样的,但是比较麻烦。
涛涛数学第二套Q31 There are 8 magazines lying on a table; 4 are fashion magazines and the other 4 are sports magazines. If 3 magazines are to be selected at random from the 8 magazines, what is the probability that at least one of the fashion magazines will be selected? A,1/2 B,2/3 C,32/35 D,11/12 E,13/14 The key is E 对大部分同学来说这题可能很简单,可我就是不会做。好像有一个什么公式的吧?跪求此类题的解题思路。先谢啦。 -- by 会员 apchy (2009/12/5 4:18:10)
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