You volunteer to help drive children at a charity event to the zoo, but you can fit only 7 of the 18 children present in your van. how many different groups of 7 children can you drive?

ANSWERS

2016-09-25 15:11:32

The answer is 19,448 different groups, using the formula from permutation and combinations C (n, r) = (n!) / (r! (n-r)!) which calculates the number of times where r objects can be chosen from n object. So, 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!) then eliminate 10! C (17,7) = (17*16*15*14*13*12*11) / (7*6*5*4*3*2*1) = (98017920)(5040) C (17,7) = 19,448 different groups

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