Question 599323:  You volunteer to help drive children at a charity event to the zoo, but you can fit only 7 of the 17 children present in your van.  How many different groups of 7 children can you drive?  
 Answer by jim_thompson5910(35256)      (Show Source): 
You can  put this solution on YOUR website! C(n,r) = (n!)/(r!(n-r)!)
 
 
C(17,7) = (17!)/(7!*(17-7)!)
 
 
C(17,7) = (17!)/(7!*10!)
 
 
C(17,7) = (17*16*15*14*13*12*11*10!)/(7!*10!)
 
 
C(17,7) = (17*16*15*14*13*12*11)/(7!)
 
 
C(17,7) = (17*16*15*14*13*12*11)/(7*6*5*4*3*2*1)
 
 
C(17,7) = (98017920)/(5040)
 
 
C(17,7) = 19448
 
 
So there are 19,448 different groups. 
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