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MCI-C Handout 6 Assignment

 
 
Picture of Wanyang Zhou
MCI-C Handout 6 Assignment
by Wanyang Zhou - Sunday, 15 April 2018, 3:34 PM
 

For number 6.18

How many words are there that contain 4 A’s and 5 B's?

I have no idea how to get started.

Could anyone help me get started on this problem?

Thanks.

 
Picture of David Reynoso
Re: MCI-C Handout 6 Assignment
by David Reynoso - Monday, 16 April 2018, 10:37 AM
 

The "word" will just be a sequence of $A$'s and $B$'s in a row. So, most likely it will not be a real English word. We could rephrase the question as: In how many ways can you arrange a sequence of $9$ letters, $4$ of them $A$'s and $5$ of them $B$'s?

 
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Picture of Patrick Zhang
Re: MCI-C Handout 6 Assignment
by Patrick Zhang - Monday, 16 April 2018, 2:58 PM
 

Hint that might be helpful but also may  not: permutate all the letters first, then divide out the ones that are the same

 
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