M ARIO F . T RIOLA

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S TATISTICS. E LEMENTARY. Section 3-4 Multiplication Rule: Basics. M ARIO F . T RIOLA. E IGHTH. E DITION. Finding the Probability of Two or More Selections. Multiple selections Multiplication Rule. Notation. P(A and B) = P(event A occurs in a first trial and - PowerPoint PPT Presentation

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1Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

MARIO F. TRIOLAMARIO F. TRIOLA EIGHTHEIGHTH

EDITIONEDITION

ELEMENTARY STATISTICS Section 3-4 Multiplication Rule: Basics

2Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

Finding the Probability of Two or More Selections

Multiple selections

Multiplication Rule

3Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

NotationP(A and B) =

P(event A occurs in a first trial and

event B occurs in a second trial)

4Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

TaTbTcTdTeFaFbFcFdFe

a

b

c

d

e

a

b

c

d

e

T

F

FIGURE 3-9 Tree Diagram of Test Answers

5Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

TaTbTcTdTeFaFbFcFdFe

a

b

c

d

e

a

b

c

d

e

T

F

FIGURE 3-9 Tree Diagram of Test Answers

6Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

TaTbTcTdTeFaFbFcFdFe

a

b

c

d

e

a

b

c

d

e

T

F

P(T) =

FIGURE 3-9 Tree Diagram of Test Answers

12

7Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

TaTbTcTdTeFaFbFcFdFe

a

b

c

d

e

a

b

c

d

e

T

F

P(T) = P(c) =

FIGURE 3-9 Tree Diagram of Test Answers

12

15

8Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

TaTbTcTdTeFaFbFcFdFe

a

b

c

d

e

a

b

c

d

e

T

F

P(T) = P(c) = P(T and c) =

FIGURE 3-9 Tree Diagram of Test Answers

12

15

110

9Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

P (both correct)

10Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

P (both correct) = P (T and c)

11Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

P (both correct) = P (T and c)

1 10

1 2

1 5

12Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

P (both correct) = P (T and c)

1 10

1 2

1 5

= •

MultiplicationRule

13Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

P (both correct) = P (T and c)

1 10

1 2

1 5

= •

MultiplicationRule

INDEPENDENT EVENTS

14Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

P(B A) represents the probability of event B occurring after it is assumed that event A has already occurred (read B A as “B given A”).

Notation for Conditional Probability

15Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

Definitions

Independent EventsTwo events A and B are independent if the occurrence of one does not affect the probability of the occurrence of the other.

Dependent EventsIf A and B are not independent, they are said to be dependent.

16Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

Formal Multiplication Rule

P(A and B) = P(A) • P(B A)

If A and B are independent events, P(B A) is really the same as P(B)

17Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

Figure 3-10 Applying the Multiplication Rule

P(A or B)

Multiplication Rule

AreA and B

independent?

P(A and B) = P(A) • P(B A)

P(A and B) = P(A) • P(B)Yes

No

18Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

Intuitive Multiplication

When finding the probability that event A occurs in one trial and B occurs in the next trial, multiply the probability of event A by the probability of event B, but be sure that the probability of event B takes into account the previous occurrence of event A.

19Chapter 3. Section 3-4. Triola, Elementary Statistics, Eighth Edition. Copyright 2001. Addison Wesley Longman

Small Samples from

Large Populations

If a sample size is no more than 5% of the size of the population, treat the selections as being independent (even if the selections are made without replacement, so they are technically dependent).