SOLUTION: Sam had 9 sweaters. If he wore one a day for a week, how many permutations are possible? My math teacher gave me a sheet of permutations to answer at the end of class and witho

Algebra ->  Permutations -> SOLUTION: Sam had 9 sweaters. If he wore one a day for a week, how many permutations are possible? My math teacher gave me a sheet of permutations to answer at the end of class and witho      Log On


   

Question 188540: Sam had 9 sweaters. If he wore one a day for a week, how many permutations are possible?
My math teacher gave me a sheet of permutations to answer at the end of class and without previous knowledge I am having a very difficult time with these questions. I am asking the one that seems the easiest so that I can try to figure out the remaining. My answer is 36 but I'm not sure if its correct or how I should have gotten there.
Thank you.
Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
With permutations the order in which the objects are arrainged is important.
nPr Arraingement of r objects selected from a total of n objects.
=9P7
=n(n-1)(n-2)*...*(n-r+1)
=n!/(n-r)! faster than the line above.
=9!/(9-7)!
=9!/2!
=9*8*7*6*5*4*3
=181440 answer.
.
Ed