o Introduction
o 9.1 Sampling Distributions
o 9.2 Sample Proportions
o 93 Sample Means
o Chapter Review
486
Chapter 9 Sampling Distributions
Introduction
INTRODUCTION
The reasoning of statistical inference rests on asking, "How often would this
method giv
I
586
chapter 10 Introduction to Inference
Inpt :Data
0: 0
6
W: 272
n: 840
P:#Po
m
a
'
P
o
.yi
J
:
Here are the results of'the z test: z = 1.449 and the Pvalue is O.Q7$;6;, .
,
,
1
'
1.
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.
1
1
:T
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,
,*

Po
z

P Value
x
n
0
i.
=275.
=I. 44914
=
.

_
10.2 Tests of significance ::359
10.2 TESTS O F SIGNIFICANCE
C onfidence intervals are one of the two most common types of statistical
inference. Use a confidence interval when your goal is to estimate a population parameter. T h e second common
.
 
10 Introduction to Inference
ACTIVITY 10 A Little Tacky!
Materials: Small box of thumbtacks
When you flip a fair coin, it is equally likely to land "heads" or "tails." Do
thumbtacks behave in the same way? In this activity, you will toss a thumbtac
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10.1 (a) 44% to 50%. (b) We do not have information about the whole population; we only know about a small sample. We expect our sample to give us a good estimate of the population value, but it will not be exa
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9
9.1
2.5003 is a parameter; x
9.2 p
7.2% is a statistic.
9.3 p
48% is a statistic; p
9.4 Both x1
335 and x2
2.5009 is a statistic.
52% is a parameter.
289 are statistics.
9.5 (a) Since the proportion of times the
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8.1 (a) No: There is no fixed n (i.e., there is no definite upper limit on the number of defects). (b) Yes: It is reasonable to believe that all responses are independent (ignoring any "peer pressure"), and all
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7.1 (a) P(less than 3) P(1 or 2)
2 6 1 3.
(b)(c) Answers vary.
7.2 (a) BBB, BBG, BGB, GBB, GGB, GBG, BGG, GGG. Each has probability 1/8. (b) Three of the eight arrangements have two (and only two) girls, so P(X
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6.1 Long trials of this experiment often approach 40% heads. One theory attributes this surprising result to a "bottlecap effect" due to an unequal rim on the penny. We don't know. But a teaching assistan
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5
5.1 The population is employed adult women, the sample is the 48 club members who returned
the survey.
5.2 (a) An individual is a person; the population is all adult U.S. residents. (b) An individual is a
househo
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4.1 (a) Since 2.54 cm 1 inch, inches are changed to centimeters by multiplying by 2.54. Letting
x
height in inches and y
height in centimeters, the transformation is y
2.54x, which is
1
monotonic increasing.
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3.1 (a) Time spent studying is explanatory; the grade is the response variable. (b) Explore the relationship; there is no reason to view one or the other as explanatory. (c) Rainfall is explanatory; crop
yiel
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2
2.1 There are many correct drawings. Here are two possibilities:
(a)
(b)
2.2 (a) The area under the curve is a rectangle with height 1 and width 1. Thus the total area under
the curve 1 1 1.
(b) 20%. (The reg
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1.1 (a) The individuals are vehicles (or cars). (b) The variables are: vehicle type (categorical),
transmission type (categorical), number of cylinders (quantitative), city MPG (quantitative), and
highway MPG
California State University, Sacramento
Department of Kinesiology & Health Science
KINS 2202 Creative Aerobics  T, R = 8:008:50 am
Office Hours: Tues. & Thurs. 11:00am 1 1:50 am
Cara Hoyt
Office: Solano 4028
Email: choyt@saclink.csus.edu
COURSE SYLLAB