-_- I'm sorry, this is going to make me look like a retard, but I'm VERY frustrated with some things and trying to do this makes my head hurt. It's very very simple I just can't use my brain.
it's a combination. 12 C 4..thanks. :-/
Well see, I got the answer 49050 but I know I got it wrong.
2007-03-18 16:26:40 · 4 answers · asked by bilbobagginz 3 in Social Science ➔ Psychology
12 C 4 is doing the following
12!
-----
4! (12-4)!
=
12!
-----
4!(8!)
=
12*11*10*9*8*7*6*5*4*3*2*1
------------------------------------------
4*3*2*1*(8*7*6*5*4*3*2*1)
so everything cancels leaving u with
12*11*10*9
-----------------
4*3*2*1
11880
--------
24
=495
2007-03-18 16:37:02 · answer #1 · answered by Riki S 2 · 2⤊ 0⤋
There's a formula for these types of probability problems. With a combination of the form 12 C 4 that formula is:
n! / (r!(n-r)!)
Where a factorial (the !) is:
x! = x * (x-1) * (x-2) ... * 1
so 3! = 3 * 2 * 1 = 6 or 6! = 6 * 5 * 4 * 3 * 2 * 1 = 720
Thus we just plug everything into the forumla...
n = 12 and r = 4
n! = 12! = 479001600
(n-r)! = 8! = 40320
r! = 4! = 24
479001600 / (40320 * 24) = 479001600 / 967680 = 495
That is, there are 495 different ways to pick 4 things for a pile of 12 things when order doesn't matter.
2007-03-18 23:41:26 · answer #2 · answered by Alex K 3 · 0⤊ 0⤋
I think the answer is 495.
2007-03-18 23:35:45 · answer #3 · answered by sam b 5 · 0⤊ 0⤋
Honestly i dont know what to do with those eighther.
2007-03-18 23:32:15 · answer #4 · answered by heather. 2 · 0⤊ 0⤋