chapter probability - st leonard's college...experimental probability of certain disasters,...
TRANSCRIPT
Chapter
Review of probability
(Consolidating)
Unions and intersections
The addition rule
Conditional probability
Two-step experiments
using tables
Using tree diagrams
Independent events
8A
8B8C8D8E
8F8G
S T A T I S T I C S A N D P R O B A B I L I T Y
Chance
Describe the results of two- and three-step chance experiments, both with and without replacement, assign probabilities to outcomes and determine probabilities of events. Investigate the concept of independence.Use the language of ‘if . . . then’, ‘given’, ‘of’, ‘knowing that’ to investigate conditional statements, and identify common mistakes when interpreting such language.(10A) Investigate reports of studies in digital media and elsewhere for information on the planning and implementation of such studies, and the reporting of variability.
What you will learn
Australian curriculum
8 Probability
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We have all heard about or experienced a disaster of some kind in Australia. Floods, bushfires or cyclones, for example, are very real possibilities in many parts of the country and, because of this, most people take out insurance to cover for any potential losses. Consequently, insurance companies try to predict the likelihood of such disasters and set their premiums
to suit. This is called risk analysis and includes calculating the experimental probability of certain disasters, depending on a number of factors. Some factors include:• geographic location• historical records of previous
disasters• local facilities, such as hospitals
and power supply• area topography.
• Chapter pre-test• Videos of all worked
examples• Interactive widgets• Interactive walkthroughs• Downloadable HOTsheets• Access to HOTmaths
Australian Curriculum courses
Online resources
Disaster probability
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• • • • •
••
•••
0.10 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10.2
impossible unlikely evenchance
likely certain
•
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4 1
23
4 1
1
23
34
4 11
2
23
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1
1
5
4
4
4
33
4
4
5
1
759
311
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Essential Mathematics for the Australian Curriculum Year 10 2ed
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Cambridge University Press
Essential Mathematics for the Australian Curriculum Year 10 2ed
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Essential Mathematics for the Australian Curriculum Year 10 2ed
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10 cm
A
B
C
10 cm 10 cm
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1
A B
n(A′ ∩ B)(B only)
n(A ∩ B′)(A only)
n(A′ ∩ B ′)(neither A nor B)
n(A ∩ B)
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n(A ∩ B′)n(A′ ∩ B)
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6
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∪ ∩ ∅
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L S
I
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••••••
•
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A
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∩ ′ ∩ ′
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∩
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∩ ′ ∪′ ∩ ∪
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••
••••
∩ ∩
∩ ∩
A B
Pr(A)
A B
Pr(A|B)
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∩
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∩
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75
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′ ∩ ′
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∩ ′ ∩ ′
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••
32 14 25
22 53
31 34 42not allowedwithout replacement
••
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∩
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Essential Mathematics for the Australian Curriculum Year 10 2ed
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R
R
B
B
Pr (R, B) = 2_9
R
R
R
R
B
R
R
B
(R, R) 1_91_91_91_91_91_91_91_91_9
(R, R)
(R, B)
(R, R)
(R, R)
(R, B)
(B, R)
(B, R)
(B, B)
Choice 1 Choice 2 Outcome Probability
2_3
2_3
2_31_
3
1_3
1_3
(R, R)
(R, B)
R
B
(B, R)
(B, B)
Pr (R, B) = 2_9
2_3
2_3
4_9
× =
2_3
1_3
2_9
× =
1_3
1_3
1_9
× =
2_3
1_3
2_9
× =
R
B
B
Choice 1 Choice 2 Outcome Probability
R
•∩
•∩
∩
2_3
2_3
2_3
1_3
1_3
1_3
R⎪R
B⎪R
R ∩ R
R ∩ B
R⎪B
B⎪B
B ∩ R
B ∩ B
R
B
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•
•
•
•••
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1_2
1_2
1_2
1_2
1_4
3_4
red
Counter Outcome ProbabilityBox
green
(A, red)
(A, green)
red
green
(B, red)
(B, green)
1_2
1_2
1_4
× =
1_2
1_2
1_4
× =
1_2
3_4
3_8
× =
1_4
1_2
1_8
× =
A
B
5_8
4_7
3_7
3_8
5_7
2_7
B
Selection 2 Outcome ProbabilitySelection 1
W
(B, B)
(B, W)
B
W
(W, B)
(W, W)
5_8
4_7
__14
× =
5_8
3_7
× =
3_8
2_7
× =
5_7
3_8
× =
B
W
5
__5615
__5615
__283
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3_8
3_8 (M, M)
(M, F) ( _________ )
( __, __ ) ( _________ )
( __, __ ) ( _________ )
3_8
3_8
__64
× =
5_8
MM
F
M
F
F
9( )
5_8
3_7
MM
F
M
F
F
(M, M) ( _________ )
( __, __ ) ( _________ )
( __, __ ) ( _________ )
( __, __ ) ( _________ )
1_2
1_4 (A, yellow)
__________
__________
________________
________
________
________
1_2
1_4
1_8
× =A
yellow
orange
yellowB
Counter Outcome ProbabilityBox
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__________
__________
__________
_____________
_____
_____
__________ ________
________
________
Falconwhite
Commodore
Colour Outcome ProbabilityCar
1_2
1_2
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A: 9 pointsB: 7 points
A winsA: 10 pointsB: 7 points
B winsA: 9 pointsB: 8 points
A winsA: 10 pointsB: 8 points
Pr(A winning)
Pr(B winning)
B winsA: 9 pointsB: 9 points
A winsA: 10 pointsB: 9 points
B winsA: 9 pointsB: 10 points
1_2
1_4
1_8
1_8
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2
A B
35
2_5
2_5
2_5
3_5
3_5
3_5
A⎪A
B⎪A
A ∩ A
A ∩ B
A⎪B
B⎪B
B ∩ A
B ∩ B
A
B
2_5
1_4
2_4
3_5
3_4
2_4
A⎪A
B⎪A
A ∩ A
A ∩ B
A⎪B
B⎪B
B ∩ A
B ∩ B
A
B
∗∩ ∩
∩
•
•
•
1
N T
45
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•• ∩
1
A B
43
2
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2
A B
14
3
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1
A B
12 2
A B
65
15
3
A B
62
4
A B
2 5
′
′
′
′
′
′
′
′
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A
2
B
4
3
1
A B
32
x
1
A B
211
x
7
x
2
B
14
A
1
A B
2x
4
∩
∩
∩ ∪
∪
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12
34
5
67
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Up for a challenge?If you get stuck on a question,check out the 'Working withunfamiliar problems' poster
at the end of the bookto help you.
∪
chee
seEx
it 1
cheese
Exit 3
cheese
Exit 2 Exit 4
Entrancestarting point
nocheese
Exit 5 cheese
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Addition rule
If A and B are mutually exclusive:Pr(A ∩ B ) = 0 andPr(A ∪ B ) = Pr(A ) + Pr(B )
Independent events
- Pr(A⎪B ) = Pr(A)
- Pr(A ∩ B ) = Pr(A ) × Pr(B )
Pr(A ∪ B ) = Pr(A ) + Pr(B ) – Pr(A ∩ B )
Unions and intersections
• Union A ∪ B (A or B )
• Intersection A ∩ B (A and B )
• Complement of A is A′′ (not A)
• A only is A ∩ B ′
• Mutually exclusive events A ∩ B =
A B
A B
A B
A B∅
A A′
Review
Sample space is the list of all possible outcomes.
Pr(event) = number of favourable outcomestotal number of outcomes
Venn diagram Two-way table
2
A B
54
1
246 6 12
51
75
Conditional probability
Pr(A⎪B ) = orPr(A ∩ B )Pr(B)
n(A ∩ B )n(B)
Pr (A⎪B ) = 27
2
A B
54
1
24
51
75
6 6 12
With replacement Without replacement
AABC
(A, A)(A, B)(A, C)
(B, A)(B, B)(B, C)
(C, A)(C, B)(C, C)
B C AABC
×(A, B)(A, C)
(B, A)×
(B, C)
(C, A)(C, B)
×
B C
Tree diagrams
With replacementChoice 1 Choice 2 Outcome Probability
Without replacement
(W, W)
(W, B)
(B, W)
(B, B)
3_7
4_7
W
B
4_7
4_7
3_7
3_7
W
B
W
B
__499
__4912
__4912
__4916
(W, W)
(W, B)
(B, W)
(B, B)
3_7
4_7
W
B
4_6
3_6
2_6
3_6
W
B
W
B
__71
__72
__72
__72
3 white4 black
Tables
Pr (1 white, 1 black) = 2_7
2_7
4_7
+
=
Probability
•
•
A A′BB′
A A′BB′
••
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∩ ∅∩ ∪
′
∩ ′′
′
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5
A B
23
1
′ ∅ ∪
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∩
′ ∩∪
∪∩ ′ ∩ ′
2
A B
35
4
′
′
1
A B
x3
3
∩ ∪
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