Understanding Basic Statistics 6th Edition by Charles Henry Brase,Corrinne Pellillo Brase

Exercise 66

Focus problems: Trick or Treat In a survey of a random sample of 35 households in the Cherry Creek neighborhood of Denver, it was found that 11 households turned out the lights and pretended not to be home on Halloween.
(a) Compute a 90% confidence interval for p , the proportion of all households in Cherry Creek that pretend not to be home on Halloween.
(b) What assumptions are necessary to calculate the confidence interval of part (a)
(c) Interpretation The national proportion of all households in the United States that turn out the lights and pretend not to be home on Halloween is 0.28. Is 0.28 in the confidence interval you computed Based on your answer, does it seem that the Cherry Creek neighborhood is much different (either a higher or lower proportion) from the population of all U.S. households Explain.