Elementary Statistics: Picturing the World (7th Edition)
7th Edition
ISBN: 9780134683416
Author: Ron Larson, Betsy Farber
Publisher: PEARSON
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Chapter 8.3, Problem 10E
Testing the Difference Between Two Means In Exercises 9–20, (a) identify the claim and state H0 and Ha, (b) find the critical value(s) and identify the rejection region(s), (c) calculate
10. SAT Scores An instructor for a SAT preparation course claims that the course will improve the test scores of students. The table shows the critical reading scores for 10 students the first two times they took the SAT. Before taking the SAT for the second time, the students took the instructor’s course to try to improve their critical reading SAT scores. At α = 0.01, is there enough evidence to support the instructor’s claim?
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For unemployed persons in the United States, the average number of months of unemployment at the end of December 2009 was approximately seven months (Bureau of Labor Statistics, January 2010). Suppose the following data are for a particular region in upstate New York. The values in the first column show the number of
months unemployed and the values in the second column show the corresponding number of unemployed persons.
Months
Unemployed
Number
Unemployed
1
1029
2
1686
3
2269
4
2675
5
3487
6
4652
7
4145
8
3587
9
2325
10
1120
Let x be a random variable indicating the number of months a person is unemployed.
a. Use the data to develop an empirical discrete probability distribution for x (to 4 decimals).
(x)
f(x)
1
2
3
4
5
6
7
8
9
10
b. Show that your probability distribution satisfies the conditions for a valid discrete probability distribution.
The input in the box below will not be graded, but may be reviewed and considered by your instructor.
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c. What is the probability that a…
West Virginia has one of the highest divorce rates in the nation, with an annual rate of approximately 5 divorces per 1000 people (Centers for Disease Control and Prevention website, January 12, 2012). The Marital Counseling Center, Inc. (MCC) thinks that the high divorce rate in the state may require them to hire additional staff.
Working with a consultant, the management of MCC has developed the following probability distribution for x = the number of new clients for marriage counseling for the next year.
Excel File: data05-19.xls
x
10
f(x)
.05
20
30
.10
.10
40
.20
50
60
.35
.20
a. Is this probability distribution valid?
- Select your answer-
Explain.
f(x)
Σf(x)
Select your answer
Select your answer
b. What is the probability MCC will obtain more than 30 new clients (to 2 decimals)?
c. What is the probability MCC will obtain fewer than 20 new clients (to 2 decimals)?
d. Compute the expected value and variance of x.
Expected value
Variance
clients per year
squared clients per year
For unemployed persons in the United States, the average number of months of unemployment at the end of December 2009 was approximately seven months (Bureau of Labor Statistics, January 2010). Suppose the following data are for a particular region in upstate New York. The values in the first column show the number of
months unemployed and the values in the second column show the corresponding number of unemployed persons.
Months
Unemployed
Number
Unemployed
1
1029
2
1686
3
2269
4
2675
5
3487
6
4652
7
4145
8
3587
9
2325
10
1120
Let x be a random variable indicating the number of months a person is unemployed.
a. Use the data to develop an empirical discrete probability distribution for x (to 4 decimals).
(x)
f(x)
1
2
3
4
5
6
7
8
9
10
b. Show that your probability distribution satisfies the conditions for a valid discrete probability distribution.
The input in the box below will not be graded, but may be reviewed and considered by your instructor.
c. What is the probability that a person…
Chapter 8 Solutions
Elementary Statistics: Picturing the World (7th Edition)
Ch. 8.1 - Classify each pair of samples as independent or...Ch. 8.1 - A survey indicates that the mean annual wages for...Ch. 8.1 - A travel agency claims that the average daily cost...Ch. 8.1 - What is the difference between two samples that...Ch. 8.1 - Explain how to perform a two-sample z-test for the...Ch. 8.1 - Describe another way you can perform a hypothesis...Ch. 8.1 - What conditions are necessary in order to use the...Ch. 8.1 - Prob. 5ECh. 8.1 - Prob. 6ECh. 8.1 - Independent and Dependent Samples In Exercises 58,...
Ch. 8.1 - Prob. 8ECh. 8.1 - In Exercises 9 and 10, use the TI-H4 Plus display...Ch. 8.1 - Prob. 10ECh. 8.1 - Prob. 11ECh. 8.1 - In Exercises 1114, test the claim about the...Ch. 8.1 - In Exercises 1114, test the claim about the...Ch. 8.1 - Prob. 14ECh. 8.1 - Testing the Difference Between Two Means In...Ch. 8.1 - Testing the Difference Between Two Means In...Ch. 8.1 - Prob. 17ECh. 8.1 - Prob. 18ECh. 8.1 - Prob. 19ECh. 8.1 - Testing the Difference Between Two Means In...Ch. 8.1 - Testing the Difference Between Two Means In...Ch. 8.1 - Prob. 22ECh. 8.1 - Prob. 23ECh. 8.1 - Prob. 24ECh. 8.1 - Prob. 25ECh. 8.1 - Getting at the Concept Explain why the null...Ch. 8.1 - Testing a Difference Other Than Zero Sometimes a...Ch. 8.1 - Testing a Difference Other Than Zero Sometimes a...Ch. 8.1 - Prob. 29ECh. 8.1 - Architect Salaries Construct a 99% confidence...Ch. 8.2 - The annual earnings of 25 people with a high...Ch. 8.2 - A manufacturer claims that the mean driving cost...Ch. 8.2 - What conditions are necessary in order to use the...Ch. 8.2 - Explain how to perform a two-sample t-test for the...Ch. 8.2 - Prob. 3ECh. 8.2 - Prob. 4ECh. 8.2 - Prob. 5ECh. 8.2 - Prob. 6ECh. 8.2 - In Exercises 38, use Table 5 in Appendix B to find...Ch. 8.2 - Prob. 8ECh. 8.2 - In Exercises 912, test the claim about the...Ch. 8.2 - Prob. 10ECh. 8.2 - Prob. 11ECh. 8.2 - In Exercises 912, test the claim about the...Ch. 8.2 - Testing the Difference Between Two Means in...Ch. 8.2 - Testing the Difference Between Two Means in...Ch. 8.2 - Testing the Difference Between Two Means in...Ch. 8.2 - Testing the Difference Between Two Means in...Ch. 8.2 - Prob. 17ECh. 8.2 - Prob. 18ECh. 8.2 - Prob. 19ECh. 8.2 - Testing the Difference Between Two Means in...Ch. 8.2 - Testing the Difference Between Two Means in...Ch. 8.2 - Testing the Difference Between Two Means in...Ch. 8.2 - Constructing Confidence Intervals for 1 2 When...Ch. 8.2 - Constructing Confidence Intervals for 1 2 When...Ch. 8.2 - Constructing Confidence Intervals for 1 2 When...Ch. 8.2 - Prob. 26ECh. 8.2 - How Protein Affects Weight Gain in Overeaters In a...Ch. 8.2 - Prob. 2CSCh. 8.2 - How Protein Affects Weight Gain in Overeaters In a...Ch. 8.2 - Prob. 4CSCh. 8.2 - Prob. 5CSCh. 8.3 - A shoe manufacturer claims that athletes can...Ch. 8.3 - Prob. 2TYCh. 8.3 - Prob. 1ECh. 8.3 - Prob. 2ECh. 8.3 - Prob. 3ECh. 8.3 - Prob. 4ECh. 8.3 - Prob. 5ECh. 8.3 - Prob. 6ECh. 8.3 - Prob. 7ECh. 8.3 - Prob. 8ECh. 8.3 - Prob. 9ECh. 8.3 - Testing the Difference Between Two Means In...Ch. 8.3 - Prob. 11ECh. 8.3 - Prob. 12ECh. 8.3 - Prob. 13ECh. 8.3 - Testing the Difference Between Two Means In...Ch. 8.3 - Prob. 15ECh. 8.3 - Prob. 16ECh. 8.3 - Testing the Difference Between Two Means In...Ch. 8.3 - Testing the Difference Between Two Means In...Ch. 8.3 - Testing the Difference Between Two Means In...Ch. 8.3 - Prob. 20ECh. 8.3 - Prob. 21ECh. 8.3 - Prob. 22ECh. 8.3 - Prob. 23ECh. 8.3 - Prob. 24ECh. 8.4 - Consider the results of the study discussed on...Ch. 8.4 - Prob. 2TYCh. 8.4 - What conditions are necessary in order to use the...Ch. 8.4 - Explain how to perform a two-sample z-test for the...Ch. 8.4 - In Exercises 36, determine whether a normal...Ch. 8.4 - Prob. 4ECh. 8.4 - Prob. 5ECh. 8.4 - In Exercises 36, determine whether a normal...Ch. 8.4 - Prob. 7ECh. 8.4 - Testing the Difference Between Two Proportions In...Ch. 8.4 - Prob. 9ECh. 8.4 - Prob. 10ECh. 8.4 - Prob. 11ECh. 8.4 - Testing the Difference Between Two Proportions In...Ch. 8.4 - Prob. 13ECh. 8.4 - Prob. 14ECh. 8.4 - Intermarriages In Exercises 1318, use the figure,...Ch. 8.4 - Prob. 16ECh. 8.4 - Prob. 17ECh. 8.4 - Intermarriages In Exercises 1318, use the figure,...Ch. 8.4 - Prob. 19ECh. 8.4 - Prob. 20ECh. 8.4 - Prob. 21ECh. 8.4 - U.S. Workforce In Exercises 1922, use the figure...Ch. 8.4 - Prob. 23ECh. 8.4 - Prob. 24ECh. 8.4 - Prob. 25ECh. 8.4 - Prob. 26ECh. 8 - Uses Hypothesis Testing with Two Samples...Ch. 8 - Medical research often involves blind and...Ch. 8 - Prob. 8.1.1RECh. 8 - Prob. 8.1.2RECh. 8 - Sample 1: The fuel efficiencies of 20 sports...Ch. 8 - Prob. 8.1.4RECh. 8 - Prob. 8.1.5RECh. 8 - In Exercises 58, test the claim about the...Ch. 8 - Prob. 8.1.7RECh. 8 - In Exercises 58, test the claim about the...Ch. 8 - In Exercises 9 and 10, (a) identify the claim and...Ch. 8 - Prob. 8.1.10RECh. 8 - Prob. 8.2.11RECh. 8 - Prob. 8.2.12RECh. 8 - Prob. 8.2.13RECh. 8 - Prob. 8.2.14RECh. 8 - Prob. 8.2.15RECh. 8 - Prob. 8.2.16RECh. 8 - Prob. 8.2.17RECh. 8 - Prob. 8.2.18RECh. 8 - Prob. 8.3.19RECh. 8 - In Exercises 1922, test the claim about the mean...Ch. 8 - Prob. 8.3.21RECh. 8 - Prob. 8.3.22RECh. 8 - Prob. 8.3.23RECh. 8 - In Exercises 23 and 24, (a) identify the claim and...Ch. 8 - Prob. 8.4.25RECh. 8 - Prob. 8.4.26RECh. 8 - Prob. 8.4.27RECh. 8 - Prob. 8.4.28RECh. 8 - Prob. 8.4.29RECh. 8 - Prob. 8.4.30RECh. 8 - Prob. 1CQCh. 8 - Prob. 2CQCh. 8 - Prob. 3CQCh. 8 - Prob. 4CQCh. 8 - Take this test as you would take a test in class....Ch. 8 - Prob. 2CTCh. 8 - A physical therapist suggests that soft tissue...Ch. 8 - Take this test as you would take a test in class....Ch. 8 - The U.S. Department of Health Human Services...Ch. 8 - Prob. 2RSRDCh. 8 - Prob. 3RSRDCh. 8 - Prob. 4RSRDCh. 8 - Prob. 1TCh. 8 - Prob. 2TCh. 8 - Prob. 3TCh. 8 - Prob. 4TCh. 8 - Prob. 5TCh. 8 - Prob. 1CRCh. 8 - Prob. 2CRCh. 8 - Prob. 3CRCh. 8 - Prob. 4CRCh. 8 - In Exercises 36, construct the indicated...Ch. 8 - In Exercises 36, construct the indicated...Ch. 8 - In Exercises 710, the statement represents a...Ch. 8 - In Exercises 710, the statement represents a...Ch. 8 - In Exercises 710, the statement represents a...Ch. 8 - In Exercises 710, the statement represents a...Ch. 8 - Prob. 11CRCh. 8 - Prob. 12CRCh. 8 - Prob. 13CRCh. 8 - Prob. 14CRCh. 8 - Prob. 15CRCh. 8 - Prob. 16CRCh. 8 - A researcher claims that 5% of people who wear...
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- In Gallup's Annual Consumption Habits Poll, telephone interviews were conducted for a random sample of 1014 adults aged 18 and over. One of the questions was "How many cups of coffee, if any, do you drink on an average day?" The following table shows the results obtained (Gallup website, August 6, 2012). Excel File: data05-23.xls Number of Cups per Day Number of Responses 0 365 264 193 3 4 or more 91 101 Define a random variable x = number of cups of coffee consumed on an average day. Let x = 4 represent four or more cups. Round your answers to four decimal places. a. Develop a probability distribution for x. x 0 1 2 3 4 f(x) b. Compute the expected value of x. cups of coffee c. Compute the variance of x. cups of coffee squared d. Suppose we are only interested in adults that drink at least one cup of coffee on an average day. For this group, let y = the number of cups of coffee consumed on an average day. Compute the expected value of y. Compare it to the expected value of x. The…arrow_forwardIn Gallup's Annual Consumption Habits Poll, telephone interviews were conducted for a random sample of 1014 adults aged 18 and over. One of the questions was "How many cups of coffee, if any, do you drink on an average day?" The following table shows the results obtained (Gallup website, August 6, 2012). Excel File: data05-23.xls Number of Cups per Day Number of Responses 0 365 264 193 2 3 4 or more 91 101 Define a random variable x = number of cups of coffee consumed on an average day. Let x = 4 represent four or more cups. Round your answers to four decimal places. a. Develop a probability distribution for x. x 0 1 2 3 f(x) b. Compute the expected value of x. cups of coffee c. Compute the variance of x. cups of coffee squared d. Suppose we are only interested in adults that drink at least one cup of coffee on an average day. For this group, let y = the number of cups of coffee consumed on an average day. Compute the expected value of y. Compare it to the expected value of x. The…arrow_forwardA technician services mailing machines at companies in the Phoenix area. Depending on the type of malfunction, the service call can take 1, 2, 3, or 4 hours. The different types of malfunctions occur at about the same frequency. Develop a probability distribution for the duration of a service call. Duration of Call x f(x) 1 2 3 4 Which of the following probability distribution graphs accurately represents the data set? Consider the required conditions for a discrete probability function, shown below.Does this probability distribution satisfy equation (5.1)?Does this probability distribution satisfy equation (5.2)? What is the probability a service call will take three hours? A service call has just come in, but the type of malfunction is unknown. It is 3:00 P.M. and service technicians usually get off at 5:00 P.M. What is the probability the service technician will have to work overtime to fix the machine today?arrow_forward
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