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there are 30 students in your class, your teacher chooses 5 students to complete the group project, what is the probability that you and your 2 best friends in the class are chosen to work in the group

 Jun 9, 2017
 #1
avatar+183 
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The probabiltiy is 3/30.

 Jun 9, 2017
 #2
avatar+98196 
+1

 

There are  C(30,5)   = 142,506 possible groups

 

Assume that the three best friends comprise part of a group.....to fill out the group, we can choose any one of 27 remaining people for the fourth member and any one of 26 remaining people for the fifth member...so  ....ther are   27 * 26  = 702 possible groups comprising the three friends and two other people

 

So  the probability that the thrre friends are chosen for the group  =

 

702 / 142,506  =

 

1 /203 ≈

 

0.4926%

 

 

cool cool cool

 Jun 9, 2017

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