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There are 15 people to choose from and 4 places to put them in. How many of the groups include Bob? (This is probability. I made up the problem because I don’t know how to do this and I have a test 4th hour!)

Respuesta :

LammettHash
If we absolutely want Bob in the group, then there are 3 remaining places to fill, and 14 people to choose from. The number of groups is then

[tex]\dbinom{14}3=\dfrac{14!}{3!(14-3)!}=\dfrac{14!}{3!11!}=\dfrac{14\cdot13\cdot12}{3!}=364[/tex]

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