By the end of this chapter, the student should be able to:
- Understand and use the terminology of probability.
- Determine whether two events are mutually exclusive or
independent.
- Calculate probabilities using the Addition Rules and Multiplication
Rules.
- Construct and interpret Contingency Tables.
- Construct and interpret Venn Diagrams (optional).
- Construct and interpret Tree Diagrams (optional).
It is often necessary to "guess" about the outcome of an event in order to make a decision.
Politicians study polls to guess their likelihood of winning an election. Teachers choose a
particular course of study based on what they think students can comprehend. Doctors
estimate the treatments needed for various diseases. You may have visited a casino where
people play games chosen because of the belief that the likelihood of winning is good. You
may have chosen your course of study based on the probable availability of jobs.
You have, more than likely, used probability. In fact, you probably have an intuitive sense of
probability. Probability deals with the chance of an event occurring. Whenever you weigh the
odds of whether or not to do your homework or to study for an exam, you are using
probability. In this chapter, you will learn to solve probability problems using a systematic
approach.
Your instructor will survey your class. Count the number of students in the class today.
- Raise your hand if you have any change in your pocket or purse. Record the
number of raised hands.
- Raise your hand if you rode a bus within the past month. Record the number of
raised hands.
- Raise your hand if you answered "yes" to BOTH of the first two questions. Record
the number of raised hands.
Use the class data as estimates of the following probabilities. P(change)P(change) means the probability
that a randomly chosen person in your class has change in his/her pocket or purse. P(bus)P(bus)
means the probability that a randomly chosen person in your class rode a bus within the last
month and so on. Discuss your answers.
- Find P(change)P(change).
- Find P(bus)P(bus).
- Find P(change and bus)P(change and bus) Find the probability that a randomly chosen student in your class
has change in his/her pocket or purse and rode a bus within the last month.
- Find P(change| bus)P(change| bus) Find the probability that a randomly chosen student has change given
that he/she rode a bus within the last month. Count all the students that rode a bus. From
the group of students who rode a bus, count those who have change. The probability is
equal to those who have change and rode a bus divided by those who rode a bus.
"This book was purchased from the authors by the Maxfield Foundation and provided to the community as an open textbook available freely online and in PDF format. Bound copies of the book can also […]"