Chapter 8, Problem 8.33AC

What is a sample space?

In a survey of 1,626,773 U.S. adults, 49,311 personally identified as lesbian, gay, bisexual, or transgender. Construct a 95% confidence interval for the population portion of U.S. adults who personally identify as gay, lesbian,bisexual or transgender.

In statistics, what is a Confidence Interval and how confidence intervals are used in research?

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.

Public Policy Polling recently conducted a survey asking adults across the U.S. about music preferences. When asked, 80 of the 571 participants admitted that they have illegally downloaded music. Create a 99% confidence interval for the true proportion of American adults who have illegally downloaded music.

To devise effective marketing strategies it is helpful to know the characteristics of your customers. A study compared the demographic characteristics of people who use the Internet for travel arrangements. Of 932 Internet users, 543 had completed college. (a) Find a 95% confidence interval for the proportion of people who use the Internet for travel arrangements, and have a college degree. (b) Can you conclude from this study that the majority of people who use the Internet for travel arrangements own a college degree? Justify your answer using the confidence interval computed in (a).

In a Gallup poll of 804 randomly selected adults living in the 50 U.S. states and the District of Columbia, 466 felt that gay and lesbian relationships were morally acceptable. Construct a 95% confidence interval for the proportion of Americans who feel that gay and lesbian relationships are morally acceptable.

Isabel Myers was a pioneer in the study of personality types. According to one of her surveys, in a sample of 62 professional actors, it was found 40 were extroverts. Construct a 98% confidence interval for the true proportion of professional actors who are extroverts.

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.