METHODS OF ASSIGNING PROBABILITY

The Uniform Probability Model

Example 1: Consider the experiment of rolling a fair die and recording the top face. The sample space can be listed as:

Example 1 (cont.) What is the probability of getting a number higher than 4 (event A)?

The Uniform Probability Model Suppose that among 50 students in a class, 42 are right-handed and 8 left-handed. A student is selected. The intuitive notion of random selection is that each student is as likely to be selected as any other. A probability for any student to be selected is: 1/50. What is the probability that the selected student is left-handed?

Long-run Relative Frequency If one corner of a die is cut off, it would be unreasonable to assume that the faces remain equally likely. When the assumption of equally likely elementary outcomes is not tenable, how do we assess the probability of an event?

Long-run Relative Frequency

Let A be the event of getting a 6 when rolling a die. If the die is rolled 100 times and 6 comes up 43 times, the observed relative frequency of A would be: 43/100=.43. Thus, we can assign P(A)=0.43

Problem: 4.17 to 4.22, 4.24 to 4.28.