1. Unit 4
Section 3.1

2. 3.1: Basic Concepts of Probability and Counting
Probability– the chance of an event occurring.
Probability event – an action, or trial, through which specific results (counts, measures, responses) are obtained.
Ex: rolling a die, flipping a coin
Outcome – the result of a single trial of a probability experiment.
Ex: flipping heads or tails
Sample Space – the set of all possible outcomes a probability experiment.

3. Determining Sample Spaces
Section 3.1
Determining Sample Spaces
Example 1: Determine the sample space for each probability experiment.
Experiment
Sample Space
Toss one coin
Roll a die
Answer a true/false question
Toss Two Coins

4. Determining Sample Space
Section 3.1
Determining Sample Space
Example 2: Determine the sample space for rolling two dice. 1 2 3 4 5 6

5. Determining Sample Space
Section 3.1
Determining Sample Space
Example 3: Determine the sample space for the gender of the children if a family has three children.
(Use B for boy and G for girl)

6. Section 3.1 Event – set of outcomes of a probability event.
Ex: rolling and odd number
Simple event – an event with only one outcome.
Ex: Flipping heads and rolling a three
Compound event – an event with more than one outcome.
Ex: Flipping heads and rolling an even
Classical (theoretical) probability – the use of sample spaces to determine the numerical probability that an event will happen.
Equally Likely Events – events that have the same probability of occurring.
Ex: flipping heads or tails.

7. Formula for Classical Probability
Section 3.1
Formula for Classical Probability
The probability of any event E is:
The number of outcomes in E
Total number of outcomes in the sample space

8. Section 3.1
Example 4:
A) For a card drawn from an ordinary deck, find the probability of getting a queen.
B) If a family has three children, find the probability that all the children are girls

9. Section 3.1
Example 5: A card is drawn from an ordinary deck. Find these probabilities:
Of getting a jack
Of getting the 6 of clubs
Of getting a 3 or a diamond
Of getting a 3 or a 6

10. Section 3.1 Probability Rules:
The probability of any event is a number between (and including) 0 and 1.
If an event cannot occur, then the probability is 0.
If an event is certain, then the probability is 1.
The sum of the probabilities of all the outcomes in the sample space is 1.

11. Section 3.1
Empirical (statistical) probability – probability that relies on actual experience to determine the likelihood of outcomes.
also known as experimental probability
Example 6 :
In a sample of 50 people, 21 had type O blood, 22 had type A blood, 5 had type B blood, and 2 had type AB blood.
Set up a frequency distribution and find the following probabilities:
A person has type O blood
A person has type A or B blood
A person does not have type AB blood

12. Section 3.1
Subjective Probability – a probability value based on an educated guess or estimate, employing opinions and inexact information.
Ex: A doctor might say that there is a 30% chance that a patient will need surgery.

13. Homework:
Pgs : 15 – 20,