Math Probability

Does order matter?

(would ab and ba be considered different?)

Yes order Matters then

Permutation

No it doesn't matter then

Combination

If there is no repitition use

n! where n is the number for the event

if there is a larger set and the data you are collecting is for a smaller set within that group use

n! / (n-r)! where r is how many you want

if there is repetition of elements use

n! / r1! * r2! ...

where r is the number of times a single element repeats

If there is replacement (you can put it back after selecting and set stays the same) use

n to r where n is # of things to chose from and r is how many of those you need for the sit

If there is no repetition use

n! / r!(n-r)!

If there is repetition use

(n+r-1)! / r! (n-1)1