G OA L : F I N D P R O B A B I L I T Y O F A C O M P O U N D E V E N T.

E L I G I B L E C O N T E N T:A 1 . 2 . 3 . 3 . 1

12-7 PROBABILITY OF COMPOUND EVENTS

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.

• 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)

TWO TYPES

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)

EXCLUSIVE EXAMPLES

You roll a 10 sided die. 1. Find the probability of rolling a 4 or an 8.

P(4 or 8) = 0.2

2. Find the probability of rolling a 9 or less than 3.

P(9 or less than 3) = 0.3

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)

INCLUSIVE EXAMPLES

You roll a 10 sided die. 1. Find the probability of rolling a 5 or an odd

number.P(5 or odd) = 0.5

2. 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:1. P(jack or king)

Exclusive – 0.15

2. P(jack or spade)Inclusive – 0.31

3. P(4 or red card)Inclusive – 0.54

4. P(face card or Ace)Exclusive – 0.31

PRACTICE

• Worksheet – “Probabilities of Compound Events”

HOMEWORK

• Worksheet – “Probability of Compound Events Homework”