Lesson 9-7 Pages 398-401

Independent and Dependent

Events

What you will learn!

How to find the probability of independent and dependent events.

Compound eventCompound eventIndependent eventIndependent eventDependent eventDependent event

What you really need to know!

A compound event consists of two or more simple events.

What you really need to know!

The probability of two events can be found by multiplying the probability of the first event by the probability of the second event.

What you really need to know!

If the outcome of one event does not affect the outcome of a second event, the events are called independent events.

What you really need to know!

If the outcome of one event affects the outcome of a second event, the events are called dependent events.

Link to Pre-Made Lesson

A number cube is rolled, and the spinner shown is spun. Find the probability of rolling a

2 and spinning a vowel.

Example 1:

6

1)2( P

5

2)( vowelP

15

1

30

2

5

2

6

1

A box contains 2 oatmeal, 3 strawberry, and 6 cinnamon snack bars. John reaches in the box and randomly takes two snack bars, one after the other. Find the probability that he will choose a cinnamon bar and then a strawberry bar.

Example 2:

11

6)( CP

10

3)( SP 55

9

110

18

10

3

11

6

Example 3:

For lunch, Jessica may choose from a turkey sandwich, a tuna sandwich, a salad, or a soup. For a drink, she can choose juice, milk, or water. If she chooses a lunch at random, what is the probability that she chooses a sandwich (of either kind) and juice?

Independent events

2

1

4

2)( swP

3

1)( jP

6

1

3

1

2

1)j and sw( P

The choice of sandwich has no affect on how many drinks there are to choose from.

Example 4:

Mrs. Tierney will select two students from her class to be on the principal’s committee. She places each name in a bag and selects one at a time. The class contains 15 girls and 12 boys. What is the probability she selects a girl’s name first, then a boy’s name?

Dependent events

9

5

27

15)( gP

13

6

26

12)( bP

39

10

13

6

9

5)b then g( P

There will be one less possibility for the second name after the first is selected.

Page 399

Guided Practice

#’s 4-5

Pages 398-399 with someone at home and study

examples!

Read:

Homework: Page 400-401

#’s 6-9, 11-19

#’s 25-32 all

Lesson Check Ch 9

Link to Lesson 9-7 Review Practice

Page

586

Lesson 9-7

Study Guide and Review

Pages

402-404

#’s 1-43(Odd answers in back of book)

Prepare for Test!

Page

405

#’s 1-16 Lesson Check Ch 9

Prepare for Test!

Pages

406-407

#’s 1-17