Solucionario devore

Chapter 1: Overview and Descriptive Statistics

CHAPTER 1
Section 1.1
1. a. b. c. d. Houston Chronicle, Des Moines Register, Chicago Tribune, Washington Post Capital One, Campbell Soup, Merrill Lynch, Pulitzer Bill Jasper, Kay Reinke, Helen Ford, David Menedez 1.78, 2.44, 3.5, 3.04

2. a. b. c. d. 29.1 yd., 28.3 yd., 24.7 yd., 31.0 yd. 432, 196, 184, 321 2.1, 4.0, 3.2, 6.3 0.07 g, 1.58 g,7.1 g, 27.2 g

3. a. In a sample of 100 VCRs, what are the chances that more than 20 need service while under warrantee? What are the chances than none need service while still under warrantee? What proportion of all VCRs of this brand and model will need service within the warrantee period?

b.

1

Chapter 1: Overview and Descriptive Statistics
4. a. Concrete: All living U.S. Citizens,all mutual funds marketed in the U.S., all books published in 1980. Hypothetical: All grade point averages for University of California undergraduates during the next academic year. Page lengths for all books published during the next calendar year. Batting averages for all major league players during the next baseball season. Concrete: Probability: In a sample of 5 mutual funds, what is the chancethat all 5 have rates of return which exceeded 10% last year? Statistics: If previous year rates-of-return for 5 mutual funds were 9.6, 14.5, 8.3, 9.9 and 10.2, can we conclude that the average rate for all funds was below 10%? Conceptual: Probability: In a sample of 10 books to be published next year, how likely is it that the average number of pages for the 10 is between 200 and 250?Statistics: If the sample average number of pages for 10 books is 227, can we be highly confident that the average for all books is between 200 and 245?

b.

5. a. No, the relevant conceptual population is all scores of all students who participate in the SI in conjunction with this particular statistics course. The advantage to randomly choosing students to participate in the two groups is that we aremore likely to get a sample representative of the population at large. If it were left to students to choose, there may be a division of abilities in the two groups which could unnecessarily affect the outcome of the experiment. If all students were put in the treatment group there would be no results with which to compare the treatments.

b.

c.

6.

One could take a simple random sampleof students from all students in the California State University system and ask each student in the sample to report the distance form their hometown to campus. Alternatively, the sample could be generated by taking a stratified random sample by taking a simple random sample from each of the 23 campuses and again asking each student in the sample to report the distance from their hometown tocampus. Certain problems might arise with self reporting of distances, such as recording error or poor recall. This study is enumerative because there exists a finite, identifiable population of objects from which to sample.

7.

One could generate a simple random sample of all single family homes in the city or a stratified random sample by taking a simple random sample from each of the 10district neighborhoods. From each of the homes in the sample the necessary variables would be collected. This would be an enumerative study because there exists a finite, identifiable population of objects from which to sample.

2

Chapter 1: Overview and Descriptive Statistics
8. a. b. Number observations equal 2 x 2 x 2 = 8 This could be called an analytic study because the data would becollected on an existing process. There is no sampling frame.

9. a. There could be several explanations for the variability of the measurements. Among them could be measuring error, (due to mechanical or technical changes across measurements), recording error, differences in weather conditions at time of measurements, etc. This could be called an analytic study because there is no sampling frame....