[問題] Please help a "vegetable bird" like me
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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