Factorial Quesitons: number of juries pulled from pool of 25

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gnarlycarly227

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a) How many different 12 member juries can be formed from a group of 25 people?

b) How many ways can 12 people be chosen for a jury out of the 25 be lined up?
 
Re: Factorial Quesitons- Please help!

gnarlycarly227 said:
a) How many different 12 member juries can be formed from a group of 25 people?

b) How many ways can 12 people be chosen for a jury out of the 25 be lined up?
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Please show us your work, indicating exactly where you are stuck - so that we know where to begin to help you.
 
Re: Factorial Quesitons- Please help!

Okay, well here is what I did so far. for a I did 25!/ 13! 12! and got 5,200,300. now i BELIEVE this is right but i'm not 100% sure. with b, i'm kind of lost.... so far i did 25 x 24 x 23x 22 x 21x 20 x 19 x 18 x17 x16x 15 x 14. my calc said 2.49095202 E15. idk if this is right so please help thanks so much!
 
Re: Factorial Quesitons- Please help!

gnarlycarly227 said:
Okay, well here is what I did so far. for a I did 25!/( 13! 12!) and got 5,200,300. now i BELIEVE this is right but i'm not 100% sure. with b, i'm kind of lost.... so far i did 25 x 24 x 23x 22 x 21x 20 x 19 x 18 x17 x16x 15 x 14. (= 25!/(25-12)!) my calc said 2.49095202 E15. idk if this is right so please help thanks so much!
Click to expand...

As far as I can tell, those are correct.

The first one is a "combination" problem - where order does not matter.

The second one is a "permutation" problem - where order does matter.

By the way, in these types of problems - it is generally preferable to leave the answer in factorial form.
 
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