posted by Math on .
I had to solve for this:
1) choose 4 people from a class of 12
12C4 = 495
2) chosse 8 people from a class of 12
12C8 = 495
why is it that they both eqaul 495? maybe I am doing it wrong but I am confused why do they both equal 495?
They are the same, both 2 from the mean of 6. If you do 12C6, you get the max. A neat thing to do is to graph each possibilty,
12C3 and so on until
Graph number combinations vs n.
If you smooth it up, you get the binomial approximation to the normal probability curve.
to go along with what bobpursley showed you, try to finish this pattern
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
to get a new number, add the one immediately above and one to the left, the left column is made up of 1's
This is Pascal's Triangle. Look at the row that starts with 1 12 ...
Did you notice something?