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A little help here? (II-B Combinatorics HW)

 
 
TangDavid的头像
A little help here? (II-B Combinatorics HW)
TangDavid - 2020年01月3日 Friday 12:03
 

Excuse me, I'm David Tang from MC2B, and I don't even know how to do 28) on Counting Methods, pt. 2.


I would like you to do a favor and give me a hint.


Thanks.


Sincerely, David Tang 2020

 
ProfessorAreteem的头像
Re: A little help here? (II-B Combinatorics HW)
ProfessorAreteem - 2020年01月3日 Friday 17:11
 

You might be tempted to use stars and bars, however, this time the balls are not identical so stars and bars would not help.

Instead start by placing $10$ balls into the first box (how many ways can you pick the $10$ balls that will go in this box?), and then place each of the remaining $20$ balls into one of the $5$ remaining boxes (you can do this one ball at a time).

Let us know if you need additional hints for this problem. Happy New Year!