# Combinatorics question

• Dec 16th 2008, 09:41 AM
Mathematicker
Combinatorics question
In the question: How many ways can a president, vice-president and treasuer be choosen from an organization with 12 members?

Would i use P(12, 3) =1320 ways
or
would i use C(12,3)x3!= 1320 ways

does it make a difference?

thanks
• Dec 16th 2008, 10:09 AM
Isomorphism
Quote:

Originally Posted by Mathematicker
In the question: How many ways can a president, vice-president and treasuer be choosen from an organization with 12 members?

Would i use P(12, 3) =1320 ways
or
would i use C(12,3)x3!= 1320 ways

does it make a difference?

thanks

Does not make a difference to the answer. But it makes a difference to the way you think.

P(12,3) says you are arranging 3 people out of 12 in some order(here the posts)

C(12,3) x 3! says first you choose 3 guys out of 12 and then you assign them their posts.

Well they are almost similar...
• Dec 16th 2008, 10:12 AM
Moo
Hello,
Actually, you can relate the two definitions.
The "P" (dunno the English name for it) is very similar to a combination problem, but you have to consider the order.

You can use both P(12,3) and C(12,3) x 3!