1. Review Question How do you find simple probability?
P(event) = Favorable Outcomes
Total Outcomes

2. 3-5 Simple Probability Day 3

3. Discussion
On homework problem #1 last night, we found the probability of picking a yellow marble to be 3/20. This meant that if we picked out a marble 40 times that we should expect to get a yellow marble 6 times.

4. Discussion
Do you think if we conducted this experiment 40 times we would pick out a yellow marble exactly 6 times?
Today, we are going to compare what math says is going to happen with what actually happens.

5. Discussion
Remember, probability just represents the chance something will happen. It doesn’t mean it is going to happen that way.
Remember our analogy of the weatherman yesterday. The weatherman makes a prediction about the weather and we see if his prediction was good or not.

6. Today’s Objective
You will be able to distinguish and compare experimental and theoretical probability.

7. Definitions
Theoretical Probability – what math says the answer is (total outcomes divided equally among possible outcomes) Experimental Probability – what real life says the answer is (what really happens out of total times)

8. Example 1
A spinner has the numbers 1-10 on it. The numbers 1-5 are shaded. Calculate the theoretical probability of each of the following events.
a. P(1) =
b. P(shaded) =
c. P(# > 7) = 

9. Example 1
You spin the spinner 20 times. You get four ones, ten shaded, and six numbers greater than seven. Calculate the experimental probability for each event.
a. P(1) =
b. P(shaded) =
c. P(# > 7) =

10. Example 1
For what events did the experimental and theoretical probabilities match?