作者RainySunDay (Heart fly)
看板GMAT
标题[问题] Please help a "vegetable bird" like me
时间Fri Sep 12 12:27:21 2008
1.How many different 6-letter sequences are there that consist of 1 A, 2 B's,
and 3 C's?
A:60
2.Apharmaceutical company received $3million in royalties on the firs $20
million in sales of the generic equivalent of one of its products and then
$9million in royalties on the next $108 million in saes. By approximately
what percent did the ratio of royalties to sales decrease from the first $20
million in sales to the next $108 million in sales?
A:45%
ps. The first question is I have a gap in memory of permutation formula
The second question is I am a little bit confused with its meaning.
Is the following equation right? [3/20-9/108]/ 9/108=87.5%
Thanks for your patience.
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1F：推 flac:1. 6(C5取2)(C3取3) 2.[3/20-9/108]/(3/20)=0.446 09/12 14:42
2F：推 thdkuo:能不能请flac大解释一下1的算法啊 @@? 09/12 14:56
3F：推 flac:补充一下 用rookie会比vegetable bird好 哈 09/12 15:21
4F：→ RainySunDay:谢谢flac。 09/13 01:32