#1,3,5,6,8,10,11,13,14.

CHAPTER 4 COLLECTING DATA 266 (a) What is the name for this k (b) Use your method from part (a) to choose the first (b) Give a possible reason why this method. 3 plots. 14. Sampling gravestones The local genealogical society 20. Timber! A lumber compan in Coles County, Illinois, has compiled records on proportion of trees in a larg all 55,914 gravestones in cemeteries in the county for cut down. They use an aeri the years 1825 to 1985. Historians plan to use these into 200 equal-sized rectan records to learn about African Americans in Coles random sample of 20 recta County's history. They first choose an SRS of 395 tree in the selected rectang records to check their accuracy by visiting the actual gravestones. a) What is the name for this l (a) Explain how you would use a random number (b) Give a possible reason wh generator to choose the SRS. Your description should this method. be clear enough for a classmate to carry out your plan. 21. How is your room? A hot (b) Use your method from part (a) to choose the first pg 259 per floor. The rooms on o 3 gravestones. water, while rooms on the 15. No tipping The owner of a large restaurant is consid There is an extra charge f ering a new "no tipping" policy and wants to survey a view. The hotel manager sample of employees. The policy would add 20% to and survey the registered the cost of food and beverages and the additional rev- rooms about his or her ov enue would be distributed equally among servers and property. kitchen staff. Describe how to select a stratified random sample of approximately 30 employees. Explain your (a) Describe how to obtain a choice of strata and why stratified random sampling stratified random samplin might be preferred in this context. strata and why this meth 16. Parking on campus The director of student life simple random sampling at a university wants to estimate the proportion of (b) Describe how to obtain undergraduate students who regularly park a car on cluster sampling. Explain campus. Describe how to select a stratified random why this method might sample of approximately 100 students. Explain your sampling. choice of strata and why stratified random sampling might be preferred in this context. 22. Go Blue! Michigan Stad 17. SRS of engineers? A corporation employs 2000 male House," seats over 100,0 and 500 female engineers. A stratified random sample The University of Michi of 200 male and 50 female engineers gives every indi- wants to survey fans abo vidual in the population the same chance to be chosen during games. Tickets a for the sample. Is it an SRS? Explain your answer. the sidelines. The cheap (where one of the auth 18. SRS of students? At a party, there are 30 students over the stadium is shown. age 21 and 20 students under age 21. You choose at random 3 of those over 21 and separately choose at random 2 of those under 21 to interview abSection 4.1 Exercises 265 credit card purchases. Surveys are mailed to 1000 of 11. Do you trust the Internet? You want to ask a sample these people, chosen at random, and 137 people return pg 256 of high school students the question "How much do the survey form. Identify the population and the sample. you trust information about health that you find on the Internet-a great deal, somewhat, not much, or not 5. Sleepless nights How much sleep do high school stu- at all?" You try out this and other questions on a pilot 09252 dents get on a typical school night? A counselor designed group of 5 students chosen from your class. a survey to find out. To make data collection easier, the counselor surveyed the first 100 students to arrive at (a) Explain how you would use a line of Table D to choose school on a particular morning. These students reported an SRS of 5 students from the following list. an average of 7.2 hours of sleep on the previous night. (b) Use line 107 to select the sample. Show how you use (a) What type of sample did the counselor obtain? each of the digits. (b) Explain why this sampling method is biased. Is 7.2 hours Anderson Drasin Kim Rider probably greater than or less than the true average amount Arroyo Eckstein Molina Rodriguez of sleep last night for all students at the school? Why? Batista Fernandez Morgan Samuels 6. Online polls Parade magazine posed the following Bell Fullmer Murphy Shen question: "Should drivers be banned from using all cell Burke Gandhi Nguyen Tse phones?" Readers were encouraged to vote online at Cabrera Garcia Palmiero Velasco parade.com. The subsequent issue of Parade reported the results: 2407 (85%) said "Yes" and 410 (15%) said "No." Calloway Glaus Percival Wallace Prince (a) What type of sample did the Parade survey obtain? Delluci Helling Washburn Deng Husain Puri Zabid (b) Explain why this sampling method is biased. Is 85% De Ramos Johnson Richards Zhao probably greater than or less than the true percent of all adults who believe that all cell phone use while driving 12. Apartment living You are planning a report on should be banned? Why? apartment living in a college town. You decide to select 7. Online reviews Many websites include customer three apartment complexes at random for in-depth reviews of products, restaurants, hotels, and so on. The interviews with residents. manager of a hotel was upset to see that 26% of review- ers on a travel website gave the hotel "1 star" - the low- (a) Explain how you would use a line of Table D to choose est possible rating. Explain how bias in the sampling an SRS of 3 complexes from the following list. method could affect the estimate. (b) Use line 117 to select the sample. Show how you use 8. Funding for fine arts The band director at a high each of the digits. school wants to estimate the percentage of parents who Ashley Oaks Country View Mayfair Village support a decrease in the budget for fine arts. Because Bay Pointe Country Villa Nobb Hill many parents attend the school's annual musical, the director surveys the first 30 parents who arrive at the Beau Jardin Crestview Pemberly Courts show. Explain how bias in the sampling method could Bluffs Del-Lynn Peppermill affect the estimate. Brandon Place Fairington Pheasant Run 9. Explain it to the congresswoman You are on the staff Briarwood Fairway Knolls Richfield of a member of Congress who is considering a bill that Brownstone Fowler Sagamore Ridge would provide government-sponsored insurance for Burberry Franklin Park Salem Courthouse nursing-home care. You report that 1 128 letters have Cambridge Georgetown Village Manor been received on the issue, of which 871 oppose the legislation. "I'm surprised that most of my constituents Chauncey Village Greenacres Waterford Court oppose the bill. I thought it would be quite popular," Country Squire Lahr House Williamsburg says the congresswoman. Are you convinced that a majority of the voters oppose the bill? How would you 13. Sampling the forest To gather data on a 1200-acre pine explain the statistical issue to the congresswoman? forest in Louisiana, the U.S. Forest Service laid a grid of 10. Sampling mall shoppers You may have seen the mall 1410 equally spaced circular plots over a map of the forest. interviewer, clipboard in hand, approaching people pass- A ground survey visited a sample of 10% of the plots. 13 ing by. Explain why even a large sample of mall shoppers (a) Explain how you would use a random number generator would not provide a trustworthy estimate of the current to choose an SRS of 141 plots. Your description should unemployment rate in the city where the mall is located. be clear enough for a classmate to carry out your plan.of individuals that select some of these clusters. All included in the sample. Ideally, clusters are but similar between." Cluster sampling saves time and money by collectiv data from entire groups of individuals that are close together. to use systematic random sampling, select a value of & based on the pop ulation size and desired sample size, randomly select a value from ] to FR identify the first individual in the sample, and choose every th individu thereafter. If there are patterns in the way the population is ordered that comcide with the value of k, the sample may not be representative of fat population. Otherwise, systematic random sampling can be easier to condine than other sampling methods. Random sampling helps avoid bias in choosing a sample. Bias can still occur in the sampling process due to undercoverage, which happens when some members of the population are less likely to be chosen or cannot be choses for the sample. Other serious problems in sample surveys can occur after the sample is cho- sen. The single biggest problem is nonresponse: when people can't be con tacted or refuse to answer. Untruthful answers by respondents, poorly worded questions, and other problems can lead to response bias. 4.1 Technology Corner TI-Nspire and other technology instructions are on the book's website at highschool.bfwpub.com/updatedtps6e. Page 254 12. Choosing an SRS Section 4.1 Exercises 1. Sampling stuffed envelopes A large retailer prepares its at random and checks the students' work. Identify the pg (249 customers' monthly credit card bills using an automatic population and the sample. machine that folds the bills, stuffs them into envelopes, and seals the envelopes for mailing. Are the envelopes 3. Students as customers A high school's student news- completely sealed? Inspectors choose 40 envelopes paper plans to survey local businesses about the impor- at random from the 1000 stuffed each hour for visual tance of students as customers. From an alphabetical inspection. Identify the population and the sample. list of all local businesses, the newspaper staff chooses 2. Student archaeologists An archaeological dig turns up 150 businesses at random. Of these, 73 return the ques- large numbers of pottery shards, broken stone tools, and tionnaire mailed by the staff. Identify the population other artifacts. Students working on the project classify and the sample. each artifact and assign a number to it. The counts in different categories are important for understanding the 4. Customer satisfaction A department store mails a cus- site, so the project director chooses 2% of the artifacts tomer satisfaction survey to people who make credit card purchases at the store. This month, 45,000 people made