ch02 JWBK035-Vince February 12, 2007 6:50 Char Count= 0
Probability Distributions 73
FIGURE 2.19 Cumulative probability function of the Bernoulli Distribution
(P=.5)
X heads in N coin tosses, etc.) is:
N′(X)=(N!/(X!∗(N−X)!))∗PX∗Q(N−X) (2.33)
where: N=The number of trials.
X=The number of successes.
P=The probability of a success on a single trial.
Q= 1 −P.
X!=X∗(X−1)∗(X−2)∗...∗ 1 (2.34)
which can be also written as:
X!=
X∏− 1
J= 0
X−J (2.34a)
Further, by convention:
0!= 1 (2.34b)