Probability

Probability: P(single event)=

Probability of more than one event P(2 events)=P(1st event) x P(2nd event)

Permutations: n things taken n at a time nPn = n! ex. 4!=4(3)(2)(1)=24
Permutations: n things taken r at a time nPr = n(n-1)... for r factors ex.
Permutations with Repetition: n things taken n at a time with repeats

Combinations: n things chosen r at a time