130 – 62 =68
=68
b.
At 99% confidence, what is the margin of error?
2.576 * Square root of ((35^2/54) + (14^2/33)
=13.78
c.
Develop a 99% confidence interval for the difference between
the two population means.
to
68 (+/) 13.78 = 54.22 to 81.78
=54.22 to 81.78
5)
Consumer Reports
uses a survey of readers to obtain customer satisfaction ratings for the
nation's largest retailers (
Consumer Reports
, March 2012). Each survey respondent is asked to
rate a specified retailer in terms of six factors: quality of products, selection, value, checkout
efficiency, service, and store layout. An overall satisfaction score summarizes the rating for
each respondent with 100 meaning the respondent is completely satisfied in terms of all six
factors. Sample data representative of independent samples of Target and Walmart customers
are shown below.
Excel File:
data1007.xls
a.
Formulate the null and alternative hypotheses to test whether there is a difference between the
population mean customer satisfaction scores the two retailers.
H
0
:
1

2
 Select your answer greater than 0greater than or
equal to
0less than 0less than or equal to
0equal to 0not equal to 0Item 1
H
a
:
1

2
 Select your answer greater than 0greater than or equal to 0less than 0less than or equal to
0equal to
0not equal to
0Item 2
b.
Assume that experience with the
Consumer Reports
satisfaction rating scale indicates that a
population standard deviation of 12
is a reasonable assumption for both retailers. Conduct
the hypothesis test and report the
p
value. Round your answer to four decimal places.
p
value =
.0138
c.
Provide a 95% confidence interval for the difference between the population mean customer
satisfaction scores for the two retailers. Which retailer, if either, appears to have the greater customer
satisfaction?
 Select your answer TargetWalmart
target
6)
Consider the following data for two independent random samples taken from two normal populations.
Excel File:
data1011.xls
a.
Compute the two sample means. (to 0 decimals)
x1 = 9
X2 =7
b.
Compute the two sample standard deviations. (to 2 decimals)
s1 = 2.28
S2 = 1.79
c.
What is the point estimate of the difference between the two population means?
9 – 7 = 2
=2
d. What is the 90% confidence interval estimate of the difference between the two population means?
(to 2 decimals)
DID NOT GET ANSWER FOR D
I think
(0.16, 4.16)
7)
The average annual cost (including tuition, room, board, books and fees) to attend a public college
takes nearly a third of the annual income of a typical family with collegeage children (
Money
, April
2012). At private colleges, the average annual cost is equal to about 60% of the typical family's
income. The following random samples show the annual cost of attending private and public colleges.
Data are in thousands of dollars. Click on the webfile logo to reference the data.
a.
Compute the sample mean and sample standard deviation for private and public colleges. Round
your answers to two decimal places.
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 Statistics, Standard Deviation, Chapter 10, Null hypothesis, Statistical hypothesis testing, Cengage Learning, Cengage Now, Cengagenowchapter10, Cengagech10