12-7 Probability of Compound Events (Or problems) Goal: Find the probability of a compound event. Eligible Content: A1.2.3.3.1

Vocabulary Prime Numbers – numbers that are only divisible by 1 and the number. 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41… The number 1 is NOT prime The number 2 is the ONLY even prime number

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.

Two Types Exclusive – two events cannot happen at the same time. Probability of rolling a 1 or a 2 on 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)

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

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

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

Mixed Problems A bag contains cards with the numbers 1-25. Find the probability of each event. 3 or even number Multiple of 3 or multiple of 7 Prime number or odd number 6 or factor of 24 5 or 15

The French Club has 16 seniors, 12 juniors, 15 sophomores, and 21 freshmen as members. What is the probability that a member chosen at random is a junior or a senior? A. 0.44 B. 1 C. 0.56 D. 0

In Mrs. Kline’s class, 7 boys have brown eyes and 5 boys have blue eyes. Out of the girls, 6 have brown eyes and 8 have blue eyes. If a student is chosen at random from the class, what is the probability that the student will be a boy or have brown eyes? A. 0.38 B. 0.69 C. 0.54 D. 0.46

Practice Worksheet – “Probabilities of Compound Events”

Homework Worksheet – “Probability of Compound Events Homework”