Chapter 8, Problem 8.46AC

Calculate and interpret a 95% confidence interval for the difference between the means of drivers and passengers. Chest Injury Rating Car Driver Passenger Car Driver Passenger 1 42 35 10 36 37 2 42 35 11 36 37 3 34 45 12 43 58 4 34 45 13 40 42 5 45 45 14 43 58 6 40 42 15 37 41 7 42 46 16 37 41 8 43 58 17 44 57 9 45 43 18 42 42

You work for a consumer advocate agency and want to find the mean repair cost of a washing machine. As part of your study, you randomly select 29 repair costs and find the mean to be $100.00 and o is $17.50. a. Construct a 90% confidence interval. b. Construct a 95% confidence interval. c. Construct a 99% confidence interval.

Russia has recently started a push for stronger smoking regulations much like those in West- ern countries concerning cigarette advertising, smoking in public places, and so on. The DATAfile named Russia contains sample data on smoking habits of Russians that are con- sistent with those reported by The Wall Street Journal (The Wall Street Journal, October 16, 2012). Analyze the data using Excel and answer the following questions. a. Develop a point estimate and a 95% confidence interval for the proportion of Russians who smoke. b. Develop a point estimate and a 95% confidence interval for the mean annual per capita consumption (number of cigarettes) of a Russian. c. For those Russians who do smoke, estimate the number of cigarettes smoked per day.

According to a Harris Interactive survey of 2401 adults conducted in April 2009, 25% of adults do not drink alcohol. Construct a 97% confidence interval for the corresponding population proportion.

3. A study was conducted to investigate where people get their news. The study included 1000 people in the age group 18-29 and 1500 people in the age group 30-55. The sample proportions of people whose main source of news is newspapers is 0.18 and 0.25 for the age groups 18-29 and 30-55, respectively. A. Find the 95% confidence interval for the difference in the proportion of people whose main source of news is newspapers for the two age groups and interpret it. В. is higher in the age group 30-55? Use the p-value method. At a=0.10, can it be concluded that the proportion of those whose source of news is newspaper

Suppose a consumer advocacy group wants to conduct a survey to find if the proportion of consumers who bought the newest generation of an MP3 player were happy with their purchase.  The survey was given to 200 customers and resulted in 175 of them being happy with their purchase.  Construct a 95% confidence interval for the population proportion.

A Businessweek/Harris survey asked senior executives at large corporations their opinions about the economic outlook for the future. One question was, "Do you think that there will be an increase in the number of full-time employees at your company over the next 12 months?" In the current survey, 220 of 400 executives answered Yes, while in a previous year survey, 192 of 400 executives had answered Yes. Provide a 95% confidence interval estimate for the difference between the proportions at the two points in time (to 4 decimals).

According to a poll, 77% of California adults (389 out of 506 surveyed) feel that education is one of the top issues facing California. We wish to construct a 90% confidence interval for the true proportion of California adults who feel that education is one of the top issues facing California.What is a point estimate for the true population proportion?

A bank report looks at what strategies and measures financial institutions are pursuing to provide mobile financial services to their customers. In a response to a survey question about barriers hindering greater consumer adoption of mobile banking, in a survey of 119 financial institutions, 78 said security concerns are a barrier, 70 said lack of trust in the technology is a barrier, and 19 said difficulty of use was a barrier. Complete parts (a) through (d) below. C a. Construct a 90% confidence interval estimate of the population proportion of financial institutions who said that security concerns are a barrier hindering greater consumer adoption of mobile banking. 0.583 ≤ 0.727 (Round to three decimal places as needed.) b. Construct a 90% confidence interval estimate of the population proportion of financial institutions who said that lack of trust is a barrier hindering greater consumer adoption of mobile banking. ST≤ 0.664 (Round to three decimal places as needed.)