you want to determine the average age of students sitting in a classroom, so you decide to take a random sample of five students. If there are thirty students sitting in class, how many different samples are possible?

Question

anonymous · Answer

is this a permutation or a combination?>

hartnn · Answer

does the order matter or not?

anonymous · Answer

I dont thikn so

hartnn · Answer

correct, it doesn't so combination

anonymous · Answer

just checked my notes.. ok..

anonymous · Answer

so then I just need to work out which is 
n C r 
n or r... does it matter which is which?

anonymous · Answer

Im getting
142506

hartnn · Answer

n is always greater than or = r

anonymous · Answer

as 
combin(30,5)
I think the sample size goes 2nd ?

anonymous · Answer

ok so the larger size goes as n

hartnn · Answer

correct,
30 C 5

anonymous · Answer

ah, intersting.. I just noticed that combin function fails if n<r

imqwerty · Answer

yea :)
30C5 is correct

anonymous · Answer

well then, I think 142506 is the answer :)

anonymous · Answer

thanks hartnn

hartnn · Answer

yes, because you can't choose 30 people from available 5 people! :P

hartnn · Answer

142506 is correct :)