Fundamental Counting Rule
MxN ways P(E)=# of ways that E occurs/total # of outcomes
Factorial Rule
N!= # of different items when all are selected
Permutations Rule (when all items are different)
nPr= Order matters. different items are available but only certain ones are selected.
Permutations rule (When some are identical)
n!/n1.n2!,n3!.....nk!number of different ways something can be arranged.
Combinations Rule
Order does not matter nCr= number of different items are available, but only so many are selected without replacement.
Classic and relative frequency probablity
p(E)=# of ways E occurs/total # of outcomes
Addition Rule (OR)
Mutually Exclusive
P(A or B)=P(A)+P(B)
Not Mutually Exclusive
P(A or B)= P(A)+P(B)-P(both)
Multiplication Rule (AND)
Independent
P(A and B)=P(A)xP(B)
Dependent
P(A and B)=P(A)xP(B/A)
Complements
"at least one" means 0 of the same item P(A)=1-P(A complement)
Conditional
P(A and B)= P(A)xP(B/A)P(B/A)=P(A+B)/P(A)Keywords- given or if