1. Lesson 12.4, For use with pages 670-674
Find the probability of selecting the following.
A red marble1. 2. Either a blue or green
marble

2. Lesson 12.4, For use with pages 670-674
Find the probability of selecting the following.
11
3ANSWER
A red marble1. 2. Either a blue or green
marble
ANSWER
11
6

3. Tree Diagrams and
the Counting Principle
Section 12.4

4. Essential Questions
• What are the differences between
permutations and combinations?
• What are the differences between odds
and probability?
• How is probability used to make
predictions?
• What are the differences between
experimental and theoretical probabilities?

5. Probability
Number of favorable outcomes
Number of possible outcomes

6. GUIDED PRACTICE for Example 4
4. Coins
Six people each flip a coin. What is the probability
of 6 heads?
STEP 1 List the favorable outcomes. There are 1.
1 x 1 x 1 x 1 x 1 x 1 = 1
STEP 2 Find the number of possible outcomes using
the counting principle.
2 2 2 2 2 2 = 64
SOLUTION

7. GUIDED PRACTICE for Example 4
STEP 3 Find the probability:
Number of favorable outcomes
Number of possible outcomes
= 64
1
ANSWER
The probability of 6 heads heads is = 64
1

8. GUIDED PRACTICE for Example 4
5. Coins Six people each flip a coin. What is the probability
they all flip the same thing?
• Does it matter what the first person flips?
• No, could be heads or tails.
• What is the probability the first person flips heads or tails?
• 2/2 or 1.
• Remember, we want all the same outcomes. So if the first
person flips a head, what does everyone else need to flip?
• Head.
• What is the probability the second person flips a head?
• ½
• The third person? The fourth? Fifth? Sixth?
• ½, ½ , ½, ½
• What is the probability they all flip the same thing?
• 2/2 x ½ x ½ x ½ x ½ x ½ = 2/64 = 1/32

9. Homework
• Worksheet 12.4
• You need to have a scientific calculator for
class tomorrow!

10. Homework
• Worksheet 12.4
• You need to have a scientific calculator for
class tomorrow!