Section 1.1 Sampling 11 22. Another sample: Draw a sample of eight animals by drawing a simple random sample of two animals from each group. What kind of sample is this? 23. Another sample: Draw a simple random sample of two groups of animals from the four groups, and construct a sample of 20 animals by including all the animals in the sampled groups. What kind of sample is this? 24. Another sample: Choose a random number between 1 and 5. Include the animal with that number in your sample, along with every fifth animal thereafter, to construct a sample of eight animals. What kind of sample is this? In Exercises 25–36, identify the kind of sample that is described. 25. Parking on campus: A college faculty consists of 400 men and 250 women. The college administration wants to draw a sample of 65 faculty members to ask their opinion about a new parking fee. They draw a simple random sample of 40 men and another simple random sample of 25 women. 26. What’s on TV? A pollster obtains a list of all the residential addresses in a certain town, and uses a computer random number generator to choose 150 of them. The pollster visits each of the 150 households and interviews all the adults in each household about their television viewing habits. 27. Cruising the mall: A pollster walks around a busy shopping mall, and approaches people passing by to ask them how often they shop at the mall. 28. Don’t drink and drive: Police at a sobriety checkpoint pull over every fifth car to determine whether the driver is sober. 29. Tell us your opinion: A television newscaster invites viewers to log on to a website to state their opinions on a proposed bill on immigration policy. More than 50,000 people express their opinions in this way. 30. Reading program: The superintendent of a large school district wants to test the effectiveness of a new program designed to improve reading skills among elementary school children. There are 30 elementary schools in the district. The superintendent chooses a simple random sample of 5 schools, and institutes the new reading program in those schools. A total of 4700 children attend these five schools. 31. Customer survey: All the customers who entered a store on a particular day were given a survey to fill out concerning their opinions of the service at the store. 32. Raffle: Five hundred people attend a charity event, and each buys a raffle ticket. The 500 ticket stubs are put in a drum and thoroughly mixed, and 10 of them are drawn. The 10 people whose tickets are drawn win a prize. 33. Hospital survey: The director of a hospital pharmacy chooses at random 100 people age 60 or older from each of three surrounding counties to ask their opinions of a new prescription drug program. 34. Bus schedule: Officials at a metropolitan transit authority want to get input from people who use a certain bus route about a possible change in the schedule. They randomly select five buses during a certain week and poll all riders on those buses about the change. 35. How much did you spend? A retailer samples 25 receipts from the past week by numbering all the receipts, generating 25 random numbers, and sampling the receipts that correspond to these numbers. 36. Phone features: A cell phone company wants to draw a sample of 600 customers to gather opinions about potential new features on upcoming phone models. The company draws a random sample of 200 from customers with Blackberry phones, a random sample of 100 from customers with LG phones, a random sample of 100 from customers with Samsung phones, and a random sample of 200 from customers with other phones. Working with the Concepts 37. You’re giving me a headache: A pharmaceutical company wants to test a new drug that is designed to provide superior relief from headaches. They want to select a sample of headache sufferers to try the drug. Do you think that it is feasible to draw a simple random sample of headache sufferers, or will it be necessary to use a sample of convenience? Explain your reasoning. 38. Pay more for recreation? The director of the recreation center at a large university wants to sample 100 students to ask them whether they would support an increase in their recreation fees in order to expand the hours that the center is open. Do you think that it is feasible to draw a simple random sample of students, or will it be necessary to use a sample of convenience? Explain your reasoning. 39. Voter preferences: A pollster wants to sample 500 voters in a town to ask them who they plan to vote for in an upcoming election. Describe a sampling method that would be appropriate in this situation. Explain your reasoning. 40. Quality control: Products come off an assembly line at the rate of several hundred per hour. It is desired to sample 10% of them to check whether they meet quality standards. Describe a sampling method that would be appropriate in this situation. Explain your reasoning. 41. On-site day care: A large company wants to sample 200 employees to ask their opinions about providing a day care center for the employees’ children. They want to be sure to sample equal numbers of men and women. Describe a sampling method that would be appropriate in this situation. Explain your reasoning.
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