E1, E2, , En are pairwise disjoint and E1 4 E2 4 4 En = S
and A be any event with nonzero probability, then
i
i
1
P(E )P(A|E )
P(E | A)
P(E )P(A|E )
i
n
j
j
j 
 
 
� A random variable is a real valued function whose domain is the sample
space of a random experiment � The probability distribution of a random variable X is the system of numbers
X
:
x1
x2