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Jenny's ballet class is going to the finals of a ballet competition. There are 25 people in her class. But for the finals group, only 10/25 (2/5) of the class is in that group. What is the probability that Jenny and her 3 best friends will be chosen?

PsychoBaker  Jun 9, 2017
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There  are   C(25,10)  = 3268760  different  groups possible

 

Jenny and her three best friends  comprise a partial group....to fill out the remaining spots we can choose any 6 of the 21 remaining people = C(21,6) =  54,264 posiible groups containing Jenny and her three best friends

 

So......the probability of this happening  =

 

 54264  / 3268760  =   21/1265 ≈ 0.0166 ≈  1.66 %

 

 

cool cool cool

CPhill  Jun 9, 2017

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