Chapter 6.2.1 Probability Models 1

• The sample space S of a random is the set of all possible outcomes
• An event is any outcome or a set of outcomes of a random phenomenon and is a subset of the sample space
• A probability model is a mathematical description of a random phenomenon consisting of two parts: a sample space S and a way of assigning probabilities to events
• For multiple events
  • create a tree diagram listing all possibilities
  • Multiplication Principle: if you can do one task in a number of ways, the both tasks can be done in a x b ways
• Any assignment of probability must obey the rules that state the basic properties of probability
• Probability Rules:
  • Any probability is a number between 0 and1.
  • All possible outcomes together must have a probability of 1. P(S)= 1
  • The Probability that an event does not occur is 1 minus the probability the event does occur.
  • If two events have no outcome in common, the probability that one or the other occurs is the sum of their individual probabilities.

Exercises: 6.11, 6.12, 6.14, 6.17, 6.18