342 / 762
342
Chapter 8: Discrete Probability Distributions
Solution:
Since
then
=
= 1.3333 (to four decimal places).
That is, if the student randomly guesses on the exam when it is taken a
repeated number of times, on average, the student will guess incorrectly after
every 1.3333 questions.
Figure 8-21
shows that the mean is 1.3333 to four
decimal places.
Section Review
8-8 The Poisson Probability Distribution
The Poisson distribution is used to model the number of occurrences within
a randomly chosen unit of time (e.g., minute, hour, day) or region (e.g., line
segment, area, volume). The distribution is named for the French
mathematician Siméon-Denis Poisson (1781–1840). For the Poisson
distribution to apply, the events must occur randomly and independently
over a continuum of time or region.
An illustration of the Poisson process is illustrated in
Figure 8-22
with the
continuum being time. Each dot (•) is an occurrence of the event of interest
Note:
Most common Poisson applications model arrivals
per unit of time
.
Figure 8-22:
Display of the Design for a Poisson Process
e-Self Review