1. Probability of Dependent Events
Section 10.3

2. Vocabulary
Dependent event - two events whose occurrence of one evvent DOES affect the likelihood that the other event will occur
Examples:
A deck of cards
Drawling a marble, without replacing it, then drawling another marble
Your teacher chooses one student to lead a group, and then chooses another student to lead another group

3. Things to Know

4. Finding the Probability of Two Dependent Events
Step 1:
Find the probability of A = P(A)
Step 2:
Find the probability of B = P(B)
Step 3:
Multiply the probability of A by the probability of B = P(A) x P(B)
Step 4:
Simplify your fraction

5. Example 1
Tell whether the events are independent or dependent. Explain.
You flip heads on one coin and tails on another coin.
Your teacher chooses one student to lead a group, and thenchooses another student to lead another group.
You choose a marble from a bag and set it aside. Then you choose another marble from the bag.
You choose a marble from a bag, record its color, and place it back into the bag. Then you choose another marble from the bag.

6. Your Turn
Tell whether the events are independent or dependent. Explain.
You choose a blue marble from a bag and set it aside. Then you choose a green marble from the bag.
You roll a 5 on a number cube and spin blue on a spinner.

7. Example 2
You randomly choose a bill from your wallet to pay for lunch. You need more money, so you choose another bill. What is the probability that you choose a $20 bill, then a $10 bill?

8. Your Turn
In Example 3, what is the probability that both bills are $20 bills?
In Example 3, what is the probability that both bills are $10 bills?

9. Example 3
You are guessing at two questions on a multiple choice test. Each question has three choices: A, B, and C.
What is the probability that you guess the correct answers to both questions?
Suppose you can eliminate one of the choices for each question. How does this change the probability that your guesses are correct?

10. Your Turn
You randomly choose two fish from the bowl. What is the probability that the first is red and without replacing it, the second is gold?

11. Green Book P. 463-464 (5-27) ALL skip #25
Assignment
Green Book P (5-27) ALL skip #25