Problems 18-19. Let p be the population proportion. In a survey of 2248 U.S. adults, 679 say they would go on vacation to Europe if cost did not matter. Round results to 3 decimal places. 18. What is the point estimate, 13, for p? 19. What is the point estimate, 4 , for q? Problems 20-22. In a survey of 5350 U.S. adults, 427 say they have traveled out of country in the past 12 months. Round your results to 3 decimal places. 20. Construct the 95% condence interval for the population proportion p. 21. Construct the 99% condence interval for the population proportion p. 22. Which of the two intervals you found is narrower? (Suggestion: plot the interval boundaries on a number line.) Problems 23-25. Online Service Usage. You are a travel agent and wish to estimate, with 92% condence, the proportion of vacationers who use an online service or the internet to make travel reservations. Your estimate must be accurate to within 5% of the population proportion. (Note: Do not use the c value for 90% or 95% to approximate the solution. Use the characteristics of c to nd the best 26 value for a 92% level of condence. See FAQ 4.11 .) 23. Assume that no preliminary estimate is available. Find the minimum sample size needed. 24. Find the minimum sample size needed, using a prior study that found that 40% of the respondents said they used an online service or the internet to make travel reservations. 25. What do you conclude about the effects of having a preliminary estimate based on your results found in questions 23 and 24