339 / 762
Chapter 8: Discrete Probability Distributions
339
Figure 8-19:
Display of the Geometric Distribution
Workbook for
Example 8-17
Example 8-18
: A student randomly guesses on a multiple-choice exam. If
the student guesses the first three questions correctly but guesses the next
question in sequence incorrectly, find the probability of this first incorrect
guess. Note: each question has four possible answers with only one correct
answer, and each question is independent of every other question.
Solution:
Observe that this can be considered as a geometric experiment.
The fixed probability of success (probability of guessing incorrectly) is 0.75.
The trials (questions) are independent of each other.
The experimental design of guessing the first incorrect answer (success) on
the 4
th
trial is displayed in
Figure 8-20
.
Click here for the Geometric Probability Distribution Workbook