1. Aug 20, 2012 #1

   jdinatale

   

   1. The problem statement, all variables and given/known data
   
   
   
   3. The attempt at a solution
   
   If at least 3 balls must be blue, then the possible ways of selecting at least 3 blues are:
   
   r, b, b, b
   b, r, b, b
   b, b, r, b
   b, b, b, r
   b, b, b, b
   
   where r = red ball, and b = blue ball
   
   So there are 5 ways to draw 3+ blue.

    

   jdinatale, Aug 20, 2012
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3. Aug 20, 2012 #2

   Dick

   

   Science Advisor

   Homework Helper

   The question didn't really spell out what 'different' means. I think they want you to treat the balls as distinguishable and probably are not concerned with the order.

    

   Dick, Aug 20, 2012
4. Aug 21, 2012 #3

   bballninja

   

   The problem with your logic is that there are 9 different blue balls and you don't account for all of them being possibly drawn.
   
   My hint for you is to consider combinations, i.e. how many ways are there to choose 3 blue balls out of 9?

    

   bballninja, Aug 21, 2012

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