Math probability
posted by Bart .
How many ways can three cars be parked in a row of four parking spaces?
I have no idea how to do this?

Can they be facing in or out? Or do they have to drive head in?
Let's assume the latter.
The first car has four spaces to choose from. That leaves the second car with three choices and the third with two. Take the product:
4 x 3 x 2 = ? 
Well, you are actually parking three cars and an empty space.
What is 4!
Let cars be aBC and E is the empty space
EABC
EACB
EBCA
EBAC
ECAB
ECBA
then you can move the E to the other three positions, you will get six in each, or 24 total, or 4! 
and, I forgot the headin/headout that DrWLS mentioned.
That makes the 4! now 4!*2*2*2 
4 x 3 x 2 = 24