Economics 309 - Spring 2016 Homework 1 Name: _______________________________________ CIN: _________________ Excel Workbook (submit via email to larroyo2@calstatela.edu by 10:00pm on April 15, 2016) Chapter 8: Exercise 8-1 (a,b) Chapter 9: Exercise 9-1, Exercise 9-2, Exercise 9-3, Exercise 9-4. Make sure to also state your answer in a sentence. Problem 6 and Problem 7 Lecture (due in class, April 13th) 1. Polls often conduct pre-election surveys by telephone. Could this bias the results? How? What if the sample is selected from the telephone book? 2. In one study, the Educational Testing Service (ETS) needed a representative sample of college students. They first divided all colleges and universities into smaller groups (e.g. one group of large public universities, another group of small private universities, etc.) They then used their judgment to select one representative school from each group. Each school in the sample was then asked to select a sample of students. Was this a good way to get a representative sample of students? Explain. 3. A cell-phone manufacturer wants to know how consumers typically use their product on a daily basis. It hires two consulting companies. MarketTech selects a random sample of 350 cell-phone users and asks whether they use their cell-phone for making phone calls, text-messaging, emailing, social media, maintain appointment, etc. Another company, Technology Research, conducts the same survey with a random sample of 75 cell-phone users. Which company will produce more accurate results? Explain. 4. \"Should US companies be allowed to outsource production?\" Rephrase this question such that the new version is likely to produce a downward bias. 5. A simple random sample of 285 part-time workers finds that the average wage is $19.43 with a standard deviation of $2.61. The data follows the normal curve. (Make sure to also state your results in a sentence.) a. b. Find a 80% confidence interval for the average wage of part-time workers. c. 6. Identify the population, sample, parameter, and statistic. As part of an effort to push for higher wages, suppose that labor unions want to know, with 99% confidence, the average wage of part-time workers to within $0.25. Determine the appropriate sample size. A research firm conducted a survey to determine the average amount steady smokers spend on cigarettes during a week. Based on 64 survey responses, the average amount spent is $20 with a standard deviation of $5. The data follows the normal curve. (Make sure to also state your results in a sentence.) a. Construct a 95% confidence interval for the average amount spent on cigarettes. 7. A simple random sample of 736 photographers found that 65% of them plan to purchase new equipment within the next year. (Make sure to also state your results in a sentence.) a. b. What is the SD of the sample? c. Find a 90% confidence interval for the percentage of photographers who plan to buy equipment. d. 8. Identify the population, sample, parameter, and statistic. A camera company will have a sale on its products if, at the 95% confidence level, 70% of all photographers plan to purchase new equipment. Will the company have the sale? A restaurant is considering changing its opening time from 9am to 8am. A survey of 172 patrons found that 116 of them prefer if the restaurant opened an hour earlier. The restaurant will change its operating hours only if, at the 99% confidence level, more than 75 percent of patrons would prefer an earlier opening time. Can you conclude that the restaurant will open at 8am? Explain