1. WARM-UP 3/20 Why is number 7 lucky?
Think of the number of ways you can make 7 on a pair of dice.
We’ll come back to this is a few minutes.

2. What’s the chance?
Unit 6 - Probability

3. MSG NOTES
Probability (P)
Number from 0 to 1 (fraction, decimal, or percent) that tells how likely an event is to occur.
0 or 0% = impossible.
1 or 100% = certain.
0.5 or 50% = even chance.

4. Probability on a Number Line
How can we express probability in words?

5. Probability
Is a ratio that compares the number of favorable outcomes to the number possible outcomes.
# of favorable outcomes
P(event) =
# of possible outcomes
MSG NOTES

6. Lucky 7 – Favorable vs. Possible Outcomes
Which number has the greatest number of ways to get the favorable outcome?
What are the total possible outcomes?
What is the probability of rolling a 7? 1
Impossible 2
1, 1 3
1, 2
2, 1 4
1, 3
2, 2
3, 1 5
1, 4
2, 3
3, 2
4, 1 6
1, 5
2, 4
3, 3
4, 2
5, 1 7
1, 6
2, 5
3, 4
4, 3
5, 2
6, 1 8
2, 6
3, 5
4, 4
5, 3
6, 2 9
3, 6
4, 5
5, 4
6, 3 10
4, 6
5, 5
6, 4 11
5, 6
6, 5 12
6, 6

7. Ex: Find the probability of not rolling a 6 on a die.
Complementary Events
Two events where one or the other must happen. Sum of these two events = 1.
P(event) + P(not event) = 1
MSG NOTES
Ex: Find the probability of not rolling a 6 on a die.
Examples:
Light is on or off
Coin lands on heads or tails
Select Chicken at Lunch or Not Chicken

8. Where do we see probability on a daily basis?

9. If there are 64 teams, what are their odds of winning the NCAA championship?

10. Think more locally. What is the chance of rain on Wednesday?
What about Thursday?
20%
100%

11. Flipping a Coin What are the chances of getting a heads? 50%
What are the chances of getting a tails?
50%
50%