 
Summary: FORMULA SHEET FOR MIDTERM I
MATH 5651, FALL 2011
INSTRUCTOR: PROF. GREG W. ANDERSON
Warning: I use the notation AB and AB interchangeably in this formula sheet.
You may also use either notation. I use AB whenever I need to keep formulas from
getting too big and ugly.
Basic rules
· 0 Pr(A) 1.
· Pr(S) = 1 (S: sample space).
· Pr() = 0 (: empty set).
· Pr(A1 · · · An) = Pr(A1) + · · · + Pr(An) for disjoint events A1, . . . , An.
· Pr(Ac
) = 1  Pr(A) (Ac
: complement of A).
· A B Pr(A) Pr(B).
· Pr(A) = Pr(AB) + Pr(ABc
).
· Pr(A B) = Pr(A) + Pr(B)  Pr(AB).
· Pr(A B C) = Pr(A) + Pr(B) + Pr(C)
 Pr(AB)  Pr(BC)  Pr(AC) + Pr(ABC).
