讨论最近的3道数学JJ，请牛人看看
8. A person went to market with a red and a green bag and bought 10 carrots & 6 radishes. On the way to home he distributed vegetables into the two bags in such a way that no bag is empty. In how many ways can he do this?

这个有好多呀。。。。怎么算？

9. In how many ways, the letters of the word POLLOLOP can be arranged?

这个也挺麻烦的 你看看

10. If 60% children like cats, 70% like dogs and 80% like rabbits then exactly how many children like all three animals?

我觉得这道题信息不足 因为没有两者重合的信息～

8 45
先考虑10个的 有9种方法 分在两个袋子里面
然后6个的 有5种方法
相乘得到45

9 560
8！除以（3！*2！*3！）

8不是45，你少考虑了14钟
只考虑期中一个袋子就行了，5*9之后还要考虑只有10个都在的，有5钟情况；6个都在的，有9钟情况
一共应该是45+5+9=59
9是560没错
10我也不会

8
10在其中一个袋子里的有6中情况，6在其中一个袋子里的有10中情况，所以总共是45＋6×2＋10×2＝77种

[ 本帖最后由 overflow 于 2008-8-19 05:19 编辑 ]

9*5+2*5+2*9+2=75

11*7-2=75

11*7-2=75 这是最直接的方法。 每种蔬菜放的可能性是11和7。考虑到不能为空，减去2

第一袋子没有c，有6种
第一袋子里有1-9个c，有7种 即7×9=63
第一个袋子有10个c，有6种
总计 63+6×2=75

赞同楼上

10. If 60% children like cats, 70% like dogs and 80% like rabbits then exactly how many children like all three animals?

My solution is:
60%+70%-1=30%, which is percentage of children who like both cats and dogs.
70%+80%-1=50%, which is percentage of children who like both dogs and rabbits.
60%+80%-1=40%, which is percentage of children who like both cats and rabitts.
(30%+50%+40%)-1=20%, which is the answer.

10. If 60% children like cats, 70% like dogs and 80% like rabbits then exactly how many children like all three animals?

My solution is:
60%+70%-1=30%, which is percentage of children who like both cats and dogs.
70%+80%-1=50%, which is percentage of children who like both dogs and rabbits.
60%+80%-1=40%, which is percentage of children who like both cats and rabitts.
(30%+50%+40%)-1=20%, which is the answer.

60%+70%-1=30%, here you ignore the percentage of children who like rabbits. I don't think this solution is right.