On January 71 20001 the Gallup Organization released the results of a poll comparing the lifestyles of today with yesteryear. The survey results were based on telephone interviews with a randomly selected national sample of 1.0.31 adults1 18 years and older1 conducted December 20-21 1999. The poll asked several questions and compared the 1999 responses with the responses given in polls taken in previous years. Below we summarize some of the poll's results?
Percentage of respondents who

Assuming that each poll was based on a randomly selected national sample of 11031 adults and that the samples in different years are independent:
a. Let p1 be the December 1999 population proportion of U.S. adults who had taken a vacation lasting six days or more within the last 12 months1 and let p2 be the December 1968 population proportion who had taken such a vacation. Calculate a 99 percent confidence interval for the difference between p1 and p2. Interpret what this interval says about how these population proportions differ.
b. Let p1 be the December 1999 population proportion of U.S. adults who took µart in some sort of daily activity to keep physically fit, and let p2 be the September 1977 population proportion who did the same. Carry out a hypothesis test to attempt to justify that the proportion who took µart in such daily activity increased from September 1977 to December 1999. Use a = .05 and explain your result.
c. Let p1 be the December 1999 population proportion of U.S. adults who watched TV more than four hours on an average weekday1 and let µ2 be the April 1981 population proportion who did the same. Carry out a hypothesis test to determine whether these population proportions differ. Use a = .05 and interpret the result of your test.
d Let p1 be the December 1999 population proportion of U.S. adults who drove a car or truck to work, and let p2 be the April 1971 population proportion who did the same. Calculate a 95 percent confidence interval for the difference between p1 and p2. On the basis of this interval1 can it be concluded that the 1999 and 1971 population proportions differ?

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Had taken a vacation lasting six days or more within the last 12 months: December 1999 42% December 1999 60% December 1999 28% December 1999 87% December 1968 62% 1 2 Took part in some sort of daily activity September 1977 48% to keep physically fit: Watched TV more than four hours on an average weekday: Drove a car or truck to work: April 1981 25% 3 April 1971 81% 4