12 -7 Probability of Compound Events

1. 12-7Probability of Compound Events Goal: Find Probability of a compound Event. Eligible Content: A1.2.3.3.1

2. Vocabulary • Compound Event – probability of two or more things happening at the same time. • Examples: • Probability of picking red or green marble. • Probability of rolling a 4 on a die and flipping a heads on a coin.

3. Two Types • Exclusive – two events cannot happen at the same time. • Probability of rolling a 1 or a 2on a 6 sided die. P(1 or 2) • Inclusive – two events can happen at the same time. • Probability of rolling a 2 or an even number. P(2 or even)

4. Exclusive Events To find probability, you must add up individual probabilities. Probability of A or B = Probability of A + Probability of B P(A or B) = P(A)+ P(B)

5. Exclusive examples You roll a 10 sided die. • Find the probability of rolling a 4 or an 8. P(4 or 8) = 0.2 • Find the probability of rolling a 9 or less than 3. P(9 or less than 3) = 0.3

6. Inclusive events To find probability, you must add up individual probabilities, then subtract the probability of both events occurring. P(A or B) = P(A) + P(B) – P(A and B)

7. Inclusive examples You roll a 10 sided die. • Find the probability of rolling a 5 or an odd number. P(5 or odd) = 0.5 • Find the probability of rolling an odd number or a prime number. P(odd or prime) = 0.6

8. Mixed Examples Using a standard deck of cards, find the probability of: • P(jack or king) Exclusive – 0.15 • P(jack or spade) Inclusive – 0.31 • P(4 or red card) Inclusive – 0.54 • P(face card or Ace) Exclusive – 0.31

9. Practice • Worksheet – “Probabilities of Compound Events”

10. Homework • Worksheet – “Probability of Compound Events Homework”